Displaying publications 41 - 60 of 996 in total

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  1. Grismer LL, Ismail LH, Awang MT, Rizal SA, Ahmad AB
    Zootaxa, 2014;3821(4):457-64.
    PMID: 24989758 DOI: 10.11646/zootaxa.3821.4.4
    A new species of scincid lizard, Lipinia sekayuensis sp. nov. from Hutan Lipur Sekayu, Terengganu State in northeastern Peninsular Malaysia is most similar to L. surda (Boulenger) but differentiated from it and all other species of Lipinia by having the combination of an adult SVL of 42.3 mm; six supralabials; five infralabials; four supraoculars; prefrontals widely separated; two loreals; fused frontoparietals; lower eyelids bearing a large, transparent disc; 21 midbody scale rows; 56 paravertertebral scale rows; 65 ventral scale rows; enlarged, precloacal scales; 10 subdigital lamellae on the third finger; 11, 15, and seven lamellae on the third, fourth, and fifth toes, respectively; distal subdigital lamellae keeled; a median row of slightly enlarged, subcaudal scales present; a generally unicolor, dark-brown dorsum bearing nine very faint, diffuse, darker stripes; and an external ear opening replaced by a scaly, auditory depression.
    Matched MeSH terms: Ecosystem
  2. Skowron Volponi MA, Volponi P
    Zookeys, 2017.
    PMID: 29133989 DOI: 10.3897/zookeys.692.13587
    A new species of clearwing moth,Pyrophleps ellawiSkowron Volponi,sp. n., is described from Peninsular Malaysia. Information on the habitat, time and conditions of occurrence, flight and mud-puddling behaviour, functional morphology, and DNA barcode are also provided. Photographs and a supplementary video from the wild demonstrate the postures and behaviour of this species ofPyrophleps, whose remaining members were described only on the basis of pinned specimens. This is the first record of this genus in Peninsular Malaysia.
    Matched MeSH terms: Ecosystem
  3. Alebraheem J, Abu-Hassan Y
    J Math Biol, 2023 Apr 27;86(5):84.
    PMID: 37103566 DOI: 10.1007/s00285-023-01914-8
    A characteristic of ecosystems is the existence of manifold of independencies which are highly complex. Various mathematical models have made considerable contributions in gaining a better understanding of the predator-prey interactions. The main components of any predator-prey models are, firstly, how the different population classes grow and secondly, how the prey and predator interacts. In this paper, the two populations' growth rates obey the logistic law and the carrying capacity of the predator depends on the available number of prey are considered. Our aim is to clarify the relationship between models and Holling types functional and numerical responses in order to gain insights into predator interferences and to answer an important question how competition is carried out. We consider a predator-prey model and a two-predator one-prey model to explain the idea. The novel approach is explained for the mechanism measurement of predator interference through depending on numerical response. Our approach gives good correspondence between an important real data and computer simulations.
    Matched MeSH terms: Ecosystem*
  4. Ismanto A, Hadibarata T, Kristanti RA, Sugianto DN, Widada S, Atmodjo W, et al.
    Mar Pollut Bull, 2023 Nov;196:115563.
    PMID: 37797535 DOI: 10.1016/j.marpolbul.2023.115563
    This study aimed to address the pressing issue of plastic pollution in aquatic ecosystems by assessing the prevalence and distribution of microplastics (MPs) in water and riverbank sediments of the Pekalongan River, a vital water source in Indonesia. From the present findings, MP concentrations in water ranged from 45.2 to 99.1 particles/L, while sediment concentrations ranged from 0.77 to 1.01 particles/g. This study revealed that fragment and film MPs constituted 30.1 % and 25.4 % of the total, respectively, with MPs measuring <1 mm and constituting 51.4 % of the total. Colored MPs, particularly blue and black MPs, accounted for 34 % of the total. The primary polymer components, as determined via Fourier transform infrared spectroscopy, were identified as polystyrene, polyester, and polyamide. In response to the escalating plastic waste crisis caused by single-use plastics, Pekalongan's local government implemented refuse segregation and recycling programs as part of its efforts to transition toward zero-waste practices.
    Matched MeSH terms: Ecosystem
  5. French MA, Fiona Barker S, Taruc RR, Ansariadi A, Duffy GA, Saifuddaolah M, et al.
    Environ Int, 2021 10;155:106679.
    PMID: 34126296 DOI: 10.1016/j.envint.2021.106679
    BACKGROUND: The intense interactions between people, animals and environmental systems in urban informal settlements compromise human and environmental health. Inadequate water and sanitation services, compounded by exposure to flooding and climate change risks, expose inhabitants to environmental contamination causing poor health and wellbeing and degrading ecosystems. However, the exact nature and full scope of risks and exposure pathways between human health and the environment in informal settlements are uncertain. Existing models are limited to microbiological linkages related to faecal-oral exposures at the individual level, and do not account for a broader range of human-environmental variables and interactions that affect population health and wellbeing.

    METHODS: We undertook a 12-month health and environmental assessment in 12 flood-prone informal settlements in Makassar, Indonesia. We obtained caregiver-reported health data, anthropometric measurements, stool and blood samples from children 

    Matched MeSH terms: Ecosystem*
  6. Chen CD, Nazni WA, Lee HL, Hashim R, Abdullah NA, Ramli R, et al.
    Trop Biomed, 2014 Jun;31(2):381-6.
    PMID: 25134909 MyJurnal
    This study reported the ant species that were recovered from monkey carcasses in three different ecological habitats in Malaysia. The study was conducted from 9 May - 10 October 2007, 6 May - 6 August 2008 and 26 May - 14 July 2009 in forested area (Gombak, Selangor), coastal area (Tanjong Sepat, Selangor) and highland area (Bukit Cincin, Pahang), respectively. Monkey carcass was used as a model for human decomposition in this study. A total of 4 replicates were used in each of the study sites. Ants were observed to prey on eggs, larvae, pupae and newly emerged flies. This study found that ant species could be found at all stages of decomposition, indicating that ants were not a significant indicator for faunal succession. However, different species of ants were obtained from monkey carcasses placed in different ecological habitats. Cardiocondyla sp. was only found on carcasses placed in the coastal area; while Pheidole longipes, Hypoponera sp. and Pachycondyla sp. were solely found on carcasses placed in the highland area. On the other hand, Pheidologeton diversus and Paratrechina longicornis were found in several ecological habitats. These data suggests that specific ant species can act as geographic indicators for different ecological habitats in forensic entomology cases in Malaysia.
    Matched MeSH terms: Ecosystem
  7. Peng W, Ma NL, Zhang D, Zhou Q, Yue X, Khoo SC, et al.
    Environ Res, 2020 12;191:110046.
    PMID: 32841638 DOI: 10.1016/j.envres.2020.110046
    Locusts differ from ordinary grasshoppers in their ability to swarm over long distances and are among the oldest migratory pests. The ecology and biology of locusts make them among the most devastating pests worldwide and hence the calls for actions to prevent the next outbreaks. The most destructive of all locust species is the desert locust (Schistocerca gregaria). Here, we review the current locust epidemic 2020 outbreak and its causes and prevention including the green technologies that may provide a reference for future directions of locust control and food security. Massive locust outbreaks threaten the terrestrial environments and crop production in around 100 countries of which Ethiopia, Somalia and Kenya are the most affected. Six large locust outbreaks are reported for the period from 1912 to 1989 all being closely related to long-term droughts and warm winters coupled with occurrence of high precipitation in spring and summer. The outbreaks in East Africa, India and Pakistan are the most pronounced with locusts migrating more than 150 km/day during which the locusts consume food equivalent to their own body weight on a daily basis. The plague heavily affects the agricultural sectors, which is the foundation of national economies and social stability. Global warming is likely the main cause of locust plague outbreak in recent decades driving egg spawning of up to 2-400,000 eggs per square meter. Biological control techniques such as microorganisms, insects and birds help to reduce the outbreaks while reducing ecosystem and agricultural impacts. In addition, green technologies such as light and sound stimulation seem to work, however, these are challenging and need further technological development incorporating remote sensing and modelling before they are applicable on large-scales. According to the Food and Agriculture Organization (FAO) of the United Nations, the 2020 locust outbreak is the worst in 70 years probably triggered by climate change, hurricanes and heavy rain and has affected a total of 70,000 ha in Somalia and Ethiopia. There is a need for shifting towards soybean, rape, and watermelon which seems to help to prevent locust outbreaks and obtain food security. Furthermore, locusts have a very high protein content and is an excellent protein source for meat production and as an alternative human protein source, which should be used to mitigate food security. In addition, forestation of arable land improves local climate conditions towards less precipitation and lower temperatures while simultaneously attracting a larger number of birds thereby increasing the locust predation rates.
    Matched MeSH terms: Ecosystem
  8. Tavakoly Sany SB, Hashim R, Rezayi M, Salleh A, Safari O
    Environ Sci Pollut Res Int, 2014 Jan;21(2):813-33.
    PMID: 24142490 DOI: 10.1007/s11356-013-2217-5
    The basic aim of this work is (1) to review and present practically operational requirements for a sustainability assessment of marine environment, such as describing the monitoring process, research approaches, objectives, guidelines, and indicators and (2) to illustrate how physico-chemical and biological indicators can be practically applied, to assess water and sediment quality in marine and coastal environment. These indicators should meet defined criteria for practical usefulness, e.g. they should be simple to understand and apply to managers and scientists with different educational backgrounds. This review aimed to encapsulate that variability, recognizing that meaningful guidance should be flexible enough to accommodate the widely differing characteristics of marine ecosystems.
    Matched MeSH terms: Ecosystem
  9. Chong XY, Vericat D, Batalla RJ, Teo FY, Lee KSP, Gibbins CN
    Sci Total Environ, 2021 Nov 10;794:148686.
    PMID: 34218154 DOI: 10.1016/j.scitotenv.2021.148686
    A major programme of dam building is underway in many of the world's tropical countries. This raises the question of whether existing research is sufficient to fully understand the impacts of dams on tropical river systems. This paper provides a systematic review of what is known about the impacts of dams on river flows, sediment dynamics and geomorphic processes in tropical rivers. The review was conducted using the SCOPUS® and Web of Science® databases, with papers analysed to look for temporal and geographic patterns in published work, assess the approaches used to help understand dam impacts, and assess the nature and magnitude of impacts on the flow regimes and geomorphology ('hydromorphology') of tropical rivers. As part of the review, a meta-analysis was used to compare key impacts across different climate regions. Although research on tropical rivers remains scarce, existing work is sufficient to allow us to draw some very broad, general conclusions about the nature of hydromorphic change: tropical dams have resulted in reductions in flow variability, lower flood peaks, reductions in sediment supply and loads, and complex geomorphic adjustments that include both channel incision and aggradation at different times and downstream distances. At this general level, impacts are consistent with those observed in other climate regions. However, studies are too few and variable in their focus to determine whether some of the more specific aspects of change observed in tropical rivers (e.g. time to reach a new, adjusted state, and downstream recovery distance) differ consistently from those in other regions. The review helps stress the need for research that incorporates before-after comparisons of flow and geomorphic conditions, and for the wider application of tools available now for assessing hydromorphic change. Very few studies have considered hydromorphic processes when designing flow operational policies for tropical dams.
    Matched MeSH terms: Ecosystem*
  10. Foon JK, Liew TS
    Zookeys, 2017.
    PMID: 29133987 DOI: 10.3897/zookeys.692.14706
    A total of 11 species and 1 subspecies of Alycaeus were recognised in Peninsular Malaysia prior to this study. However, these taxonomic descriptions of Alycaeus taxa were based on limited numbers of examined materials, where a whole spectrum of morphological variations were not accounted for and diagnoses were often provided without sufficient comparison between congeners from across the peninsula. We reviewed Peninsular Malaysian Alycaeus through the examination of 5137 specimens in 522 collection lots from all major museum collections and literature sources. Based on these examined materials, we utilised a more comprehensive revised set of 39 shell and operculum characters, as well as living animal colour to describe all Alycaeus species in this paper. We also noted their habitat and ecology, as well as updated the distribution of each species. Of the 12 previously described taxa, 10 are reconfirmed as present on Peninsular Malaysia (Alycaeus balingensis, Alycaeus carinata, Alycaeus conformis, Alycaeus gibbosulus, Alycaeus kapayanensis, Alycaeus kelantanensis, Alycaeus liratulus, Alycaeus perakensis perakensis, Alycaeus perakensis altispirus and Alycaeus thieroti) and 2 are confirmed as absent from the peninsula (Alycaeus jagori and Alycaeus pyramidalis). A new record of Alycaeus robeleni is reported for Peninsular Malaysia. One species, Chamalycaeus jousseaumei is confirmed as present on the peninsula and is reassigned to Alycaeus. The subspecies Alycaeus perakensis altispirus Möllendorff, 1902, is elevated to species. Examined Peninsular Malaysian materials that do not fit previously recognised species are described as new species. A total of 11 new species are proposed (Alycaeus selangoriensissp. n., Alycaeus costacrassasp. n., Alycaeus ikanensissp. n., Alycaeus alticolasp. n., Alycaeus charasensissp. n., Alycaeus kurauensissp. n., Alycaeus regalissp. n., Alycaeus virgogravidasp. n., Alycaeus senyumensissp. n., Alycaeus expansussp. n., Alycaeus clementsisp. n.). Overall, 23 species of Alycaeus are now recognised in Peninsular Malaysia.
    Matched MeSH terms: Ecosystem
  11. Wei Z, Van Le Q, Peng W, Yang Y, Yang H, Gu H, et al.
    J Hazard Mater, 2021 02 05;403:123658.
    PMID: 33264867 DOI: 10.1016/j.jhazmat.2020.123658
    There is a global need to use plants to restore the ecological environment. There is no systematic review of phytoremediation mechanisms and the parameters for environmental pollution. Here, we review this situation and describe the purification rate of different plants for different pollutants, as well as methods to improve the purification rate of plants. This is needed to promote the use of plants to restore the ecosystems and the environment. We found that plants mainly use their own metabolism including the interaction with microorganisms to repair their ecological environment. In the process of remediation, the purification factors of plants are affected by many conditions such as light intensity, stomatal conductance, temperature and microbial species. In addition the efficiency of phytoremediation is depending on the plants species-specific metabolism including air absorption and photosynthesis, diversity of soil microorganisms and heavy metal uptake. Although the use of nanomaterials and compost promote the restoration of plants to the environment, a high dose may have negative impacts on the plants. In order to improve the practicability of the phytoremediation on environmental restoration, further research is needed to study the effects of different kinds of catalysts on the efficiency of phytoremediation. Thus, the present review provides a recent update for development and applications of phytoremediation in different environments including air, water, and soil.
    Matched MeSH terms: Ecosystem
  12. Last PR, Naylor GJ, Manjaji-Matsumoto BM
    Zootaxa, 2016 Jul 21;4139(3):345-68.
    PMID: 27470808 DOI: 10.11646/zootaxa.4139.3.2
    The higher-level taxonomy of the stingrays (Dasyatidae) has never been comprehensively reviewed. Recent phylogenetic studies, supported by morphological data, have provided evidence that the group is monophyletic and consists of four major subgroups, the subfamilies Dasyatinae, Neotrygoninae, Urogymninae and Hypolophinae. A morphologically based review of 89 currently recognised species, undertaken for a guide to the world's rays, indicated that most of the currently recognised dasyatid genera are not monophyletic groups. These findings were supported by molecular analyses using the NADH2 gene for about 77 of these species, and this topology is supported by preliminary analyses base on whole mitochondrial genome comparisons. These molecular analyses, based on data generated from the Chondrichthyan Tree of Life project, are the most taxon-rich data available for this family. Material from all of the presently recognised genera (Dasyatis, Pteroplatytrygon and Taeniurops [Dasyatinae]; Neotrygon and Taeniura [Neotrygoninae]; Himantura and Urogymnus [Urogymninae]; and Makararaja and Pastinachus [Hypolophinae]), are included and their validity largely supported. Urogymnus and the two most species rich genera, Dasyatis and Himantura, are not considered to be monophyletic and were redefined based on external morphology. Seven new genus-level taxa are erected (Megatrygon and Telatrygon [Dasyatinae]; Brevitrygon, Fluvitrygon, Fontitrygon, Maculabatis and Pateobatis [Urogymninae], and an additional three (Bathytoshia, Hemitrygon and Hypanus [Dasyatinae]) are resurrected from the synonymy of Dasyatis. The monotypic genus Megatrygon clustered with 'amphi-American Himantura' outside the Dasyatidae, and instead as the sister group of the Potamotrygonidae and Urotrygonidae. Megatrygon is provisionally retained in the Dasyatinae pending further investigation of its internal anatomy. The morphologically divergent groups, Bathytoshia and Pteroplatytrygon, possibly form a single monophyletic group so further investigation is needed to confirm the validity of Pteroplatytrygon. A reclassification of the family Dasyatidae is provided and the above taxa are defined based on new morphological data.
    Matched MeSH terms: Ecosystem
  13. Srisonchai R, Enghoff H, Likhitrakarn N, Panha S
    Zookeys, 2018.
    PMID: 30505161 DOI: 10.3897/zookeys.797.29510
    Nine new species constituting the 'spiny' group of dragon millipedes are assigned to the new genus Spinaxytes Srisonchai, Enghoff & Panha, gen. n. Seven new species are described from Thailand: S.biloba Srisonchai, Enghoff & Panha, sp. n. and S.palmata Srisonchai, Enghoff & Panha, sp. n. from Surat Thani Province, S.hasta Srisonchai, Enghoff & Panha, sp. n. from Chumphon Province, S.krabiensis Srisonchai, Enghoff & Panha, sp. n. (type species) and S.sutchariti Srisonchai, Enghoff & Panha, sp. n. from Krabi Province, S.uncus Srisonchai, Enghoff & Panha, sp. n., and S.macaca Srisonchai, Enghoff & Panha, sp. n. from Phang Nga Province; as well as one from Malaysia, S.tortioverpa Srisonchai, Enghoff & Panha, sp. n., and one from Myanmar, S.efefi Srisonchai, Enghoff & Panha, sp. n. The new genus is endemic to South Myanmar, South Thailand, and Malaysia, and all new species are restricted to limestone habitats. All were exclusively found living on humid rock walls and/or inside small caves. Complete illustrations of external morphological characters, an identification key, and a distribution map are provided.
    Matched MeSH terms: Ecosystem
  14. Deein G, Tangjitjaroen W, Page LM
    Zootaxa, 2014;3779:341-52.
    PMID: 24871728 DOI: 10.11646/zootaxa.3779.3.2
    Lepidocephalus has been assumed to include only two species and confined to peninsular Malaysia and Indonesia. However, based on records and collections reported herein, the genus contains five species and is most common in the Chao Phraya basin of Thailand. Large rivers seem to be the preferred habitat, and difficulty in collecting these rivers may account for the paucity of specimens in collections. The known range of these five species includes western and southern Borneo, Java, Sumatra, peninsular Malaysia, and central Thailand.
    Matched MeSH terms: Ecosystem
  15. Wan Mahari WA, Waiho K, Azwar E, Fazhan H, Peng W, Ishak SD, et al.
    Chemosphere, 2022 Feb;288(Pt 2):132559.
    PMID: 34655643 DOI: 10.1016/j.chemosphere.2021.132559
    Global production of shellfish aquaculture is steadily increasing owing to the growing market demands for shellfish. The intensification of shellfish aquaculture to maximize production rate has led to increased generation of aquaculture waste streams, particularly the effluents and shellfish wastes. If not effectively managed, these wastes could pose serious threats to human health and the ecosystem while compromising the overall sustainability of the industry. The present work comprehensively reviews the source, composition, and environmental implications of shellfish wastes and aquaculture wastewater. Moreover, recent advancements in the valorization of shellfish wastes into value-added biochar via emerging thermochemical and modification techniques are scrutinized. The utilization of the produced biochar in removing emerging pollutants from aquaculture wastewater is also discussed. It was revealed that shellfish waste-derived biochar exhibits relatively higher adsorption capacities (300-1500 mg/g) compared to lignocellulose biochar (<200 mg/g). The shellfish waste-derived biochar can be effectively employed for the removal of various contaminants such as antibiotics, heavy metals, and excessive nutrients from aquaculture wastewater. Finally, future research priorities and challenges faced to improve the sustainability of the shellfish aquaculture industry to effectively support global food security are elaborated. This review envisages that future studies should focus on the biorefinery concept to extract more useful compounds (e.g., carotenoid, chitin) from shellfish wastes for promoting environmental-friendly aquaculture.
    Matched MeSH terms: Ecosystem*
  16. Mariana A, Zuraidawati Z, Ho TM, Mohd Kulaimi B, Saleh I, Shukor MN, et al.
    PMID: 16438136
    A survey of ticks and other ectoparasites was carried out during a national biodiversity scientific expedition at Gunung Stong Forest Reserve, Kelantan, Malaysia from 23-29 May 2003. A total of 272 animals comprised of 12 species of birds, 21 species of bats, 7 species of rodents and 2 species of insects were examined for ticks and other ectoparasites. From these animals, 5 species in 4 genera of ticks; 7 species in 2 families of Mesostigmatid mites and 5 species of chiggers were collected. Among the ectoparasites found were Ixodes granulatus and Leptotrombidium deliense, which are of known medical importance. A tick island consisting of 10 nymphal stages of Dermacentor spp was observed feeding on Rattus tiomanicus.
    Matched MeSH terms: Ecosystem
  17. Kessler M, Jonas R, Cicuzza D, Kluge J, Piatek K, Naks P, et al.
    Plant Biol (Stuttg), 2010 Sep 1;12(5):788-93.
    PMID: 20701702 DOI: 10.1111/j.1438-8677.2009.00270.x
    The colonisation of land by plants may not have been possible without mycorrhizae, which supply the majority of land plants with nutrients, water and other benefits. In this sense, the mycorrhization of basal groups of land plants such as ferns and lycophytes is of particular interest, yet only about 9% of fern and lycophyte species have been sampled for their mycorrhization status, and no community-level analyses exist for tropical fern communities. In the present study, we screened 170 specimens of ferns and lycophytes from Malaysia and Sulawesi (Indonesia), representing 126 species, and report the mycorrhization status for 109 species and 19 genera for the first time. Mycorrhizal colonisations were detected in 96 (56.5%) of the specimens, 85 of which corresponded to arbuscular mycorrhizae (AMF), three to dark-septate endophytes (DSE) and four to mixed colonisations (AMF + DSE). DSE colonisations were lower than in comparable samples of ferns from the Andes, suggesting a geographical or taxonomic pattern in this type of colonisation. Epiphytes had significantly lower levels of colonisation (26.1%) than terrestrial plants (70.7%), probably due to the difficulty of establishment of mycorrhizal fungi in the canopy habitat.
    Matched MeSH terms: Ecosystem*
  18. Bombieri G, Penteriani V, Almasieh K, Ambarlı H, Ashrafzadeh MR, Das CS, et al.
    PLoS Biol, 2023 Jan;21(1):e3001946.
    PMID: 36719873 DOI: 10.1371/journal.pbio.3001946
    Large carnivores have long fascinated human societies and have profound influences on ecosystems. However, their conservation represents one of the greatest challenges of our time, particularly where attacks on humans occur. Where human recreational and/or livelihood activities overlap with large carnivore ranges, conflicts can become particularly serious. Two different scenarios are responsible for such overlap: In some regions of the world, increasing human populations lead to extended encroachment into large carnivore ranges, which are subject to increasing contraction, fragmentation, and degradation. In other regions, human and large carnivore populations are expanding, thus exacerbating conflicts, especially in those areas where these species were extirpated and are now returning. We thus face the problem of learning how to live with species that can pose serious threats to humans. We collected a total of 5,440 large carnivore (Felidae, Canidae, and Ursidae; 12 species) attacks worldwide between 1950 and 2019. The number of reported attacks increased over time, especially in lower-income countries. Most attacks (68%) resulted in human injuries, whereas 32% were fatal. Although attack scenarios varied greatly within and among species, as well as in different areas of the world, factors triggering large carnivore attacks on humans largely depend on the socioeconomic context, with people being at risk mainly during recreational activities in high-income countries and during livelihood activities in low-income countries. The specific combination of local socioeconomic and ecological factors is thus a risky mix triggering large carnivore attacks on humans, whose circumstances and frequencies cannot only be ascribed to the animal species. This also implies that effective measures to reduce large carnivore attacks must also consider the diverse local ecological and social contexts.
    Matched MeSH terms: Ecosystem
  19. Rahman MA, Uehara T, Arshad A, Yusoff FM, Shamsudin MN
    J Zhejiang Univ Sci B, 2012 Oct;13(10):797-810.
    PMID: 23024047
    Two reef margin species of tropical sea urchins, Echinometra sp. C (Ec) and Echinometra oblonga (Eo), occur sympatrically on Okinawa intertidal reefs in southern Japan. Hybridization between these species was examined through a series of cross-fertilization experiments. At limited sperm concentrations, where conspecific crosses reached near 100% fertilization, both heterospecific crosses showed high fertilization rates (81%-85%). The compatibility of the gametes demonstrated that if gamete recognition molecules are involved in fertilization of these species, they are not strongly species-specific. We found that conspecific crosses reached peak fertilization levels much faster than did heterospecific crosses, indicating the presence of a prezygotic barrier to hybridization in the gametes. Larval survival, metamorphosis, and juvenile and adult survival of hybrid groups were nearly identical to those of their parent species. Hybrids from crosses in both directions developed normally through larval stages to sexually mature adults, indicating that neither gametic incompatibility nor hybrid inviability appeared to maintain reproductive isolation between these species. In adults, Ec×Ec crosses gave the highest live weight, followed by Eo (ova)×Ec (sperm), Ec (ova)×Eo (sperm), and Eo×Eo. Other growth performance measures (viz., test size, Aristotle's lantern length, and gonad index) of hybrid groups and their parental siblings showed the same trends. The phenotypic color patterns of the hybrids were closer to the maternal coloration, whereas spine length, tube-foot and gonad spicule characteristics, pedicellaria valve length, and gamete sizes showed intermediate features. Adult F(1) hybrids were completely fertile and displayed high fertilization success in F(1) backcrosses, eliminating the likelihood that hybrid sterility is a postzygotic mechanism of reproductive isolation. Conversely, intensive surveys failed to find hybrid individuals in the field, suggesting the lack or rarity of natural hybridization. This strongly suggests that reproductive isolation is achieved by prezygotic isolating mechanism(s). Of these mechanisms, habitat segregation, gamete competition, differences in spawning times, gametic incompatibility or other genetic and non-genetic factors appear to be important in maintaining the integrity of these species.
    Matched MeSH terms: Ecosystem
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