scholarly journals Extinction filters mediate the global effects of habitat fragmentation on animals

Science ◽  
2019 ◽  
Vol 366 (6470) ◽  
pp. 1236-1239 ◽  
Author(s):  
Matthew G. Betts ◽  
Christopher Wolf ◽  
Marion Pfeifer ◽  
Cristina Banks-Leite ◽  
Víctor Arroyo-Rodríguez ◽  
...  
Keyword(s):  
Habitat Fragmentation ◽  
Tropical Forests ◽  
Animal Species ◽  
Latitudinal Gradient ◽  
Spatial Arrangement ◽  
High Latitudes ◽  
Sensitive Species ◽  
Primary Driver ◽  
Biodiversity Decline ◽  
Fragmentation Sensitivity

Habitat loss is the primary driver of biodiversity decline worldwide, but the effects of fragmentation (the spatial arrangement of remaining habitat) are debated. We tested the hypothesis that forest fragmentation sensitivity—affected by avoidance of habitat edges—should be driven by historical exposure to, and therefore species’ evolutionary responses to disturbance. Using a database containing 73 datasets collected worldwide (encompassing 4489 animal species), we found that the proportion of fragmentation-sensitive species was nearly three times as high in regions with low rates of historical disturbance compared with regions with high rates of disturbance (i.e., fires, glaciation, hurricanes, and deforestation). These disturbances coincide with a latitudinal gradient in which sensitivity increases sixfold at low versus high latitudes. We conclude that conservation efforts to limit edges created by fragmentation will be most important in the world’s tropical forests.

No Evidence of Low Genetic Diversity Despite High Levels of Inbreeding and Poor Genetic Connectivity Among Tetrastigma loheri (Vitaceae) Populations in Remaining Forest Areas in Cebu, Philippines

2021 ◽  
Vol 46 (4) ◽  
pp. 951-961
Author(s):  
Jasper John A. Obico ◽  
Hemres Alburo ◽  
Julie F. Barcelona ◽  
Marie Hale ◽  
Lisa Paguntalan ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Habitat Fragmentation ◽  
Tropical Forests ◽  
Forest Cover ◽  
Genetic Connectivity ◽  
Philippine Island ◽  
Low Genetic Diversity ◽  
History Of ◽  
Gap Data ◽  
The Impact

Abstract— Little is known about the effects of habitat fragmentation on the patterns of genetic diversity and genetic connectivity of species in the remaining tropical forests of Southeast Asia. This is particularly evident in Cebu, a Philippine island that has a long history of deforestation and has lost nearly all of its forest cover. To begin filling this gap, data from 13 microsatellite loci developed for Tetrastigma loheri (Vitaceae), a common vine species in Philippine forests, were used to study patterns of genetic diversity and genetic connectivity for the four largest of the remaining forest areas in Cebu. Evidence of relatively high levels of inbreeding was found in all four areas, despite no evidence of low genetic diversity. The four areas are genetically differentiated, suggesting low genetic connectivity. The presence of inbreeding and low genetic connectivity in a commonly encountered species such as T. loheri in Cebu suggests that the impact of habitat fragmentation is likely greater on rare plant species with more restricted distributions in Cebu. Conservation recommendations for the remaining forest areas in Cebu include the establishment of steppingstone corridors between nearby areas to improve the movement of pollinators and seed dispersers among them.

scholarly journals Larger chimpanzee-dispersed seeds are elongated at Mahale, Tanzania: possible consequence of plant–disperser interaction?

2015 ◽  
Vol 31 (2) ◽  
pp. 183-186 ◽  
Author(s):  
Michio Nakamura ◽  
Noriko Itoh
Keyword(s):  
Digestive Tract ◽  
Tropical Forests ◽  
Plant Species ◽  
Seed Size ◽  
National Park ◽  
Animal Species ◽  
Food Selection ◽  
Long Distance ◽  
Mahale Mountains National Park ◽  
Round Seed

Abstract:Apes are important long-distance dispersers of large seeds in African tropical forests. Seed size and shape are likely to affect the ease of swallowing for an animal species. If an endozoochorous seed is larger than the digestive tract of an animal, the seed cannot be swallowed, and a round seed is more difficult to swallow than an elongated seed of the same length. In order to test if such a correlation exists between the seed size and its shape, we investigated the length and width of chimpanzee-dispersed seeds at the Mahale Mountains National Park, Tanzania. Among the 14 species of seeds, longer seeds had significantly narrower relative widths, and thus, they were more ovoid. Since the chimpanzee is the largest arboreal frugivore at Mahale, their food selection might have influenced the shape of larger seeds. The chimpanzee's selective consumption of such fruits with longer, elongated seeds may have facilitated the selective dispersal of such plant species in that area.

scholarly journals Species packing and the latitudinal gradient in local beta-diversity

2020 ◽  
Author(s):  
Ke Cao ◽  
Richard Condit ◽  
Xiangcheng Mi ◽  
Lei Chen ◽  
Haibao Ren ◽  
...  
Keyword(s):  
Species Richness ◽  
Tropical Forests ◽  
Beta Diversity ◽  
Latitudinal Gradient ◽  
Sampling Bias ◽  
Small Samples ◽  
Gamma Diversity ◽  
Species Packing ◽  
High Gamma ◽  
Declining Species

AbstractThe latitudinal gradient of declining species richness at higher latitudes is among the most fundamental patterns in ecology. However, whether changes in species composition across space (beta-diversity) contribute to this global gradient of species richness remains debated. Previous studies that failed to resolve the issue suffered from a well-known tendency for small samples in high gamma-diversity areas to inflate measures of beta-diversity. We provide here a rigorous test, comparing species-packing and local heterogeneity across a latitudinal gradient in tree species richness in Asia, using beta-diversity metrics that correct the gamma-diversity and sampling bias. Our data include 21 large forest plots across a wide environmental gradient in East Asia. We demonstrate that local beta-diversity increases with topographic heterogeneity, but after accounting for this and correcting the gamma-diversity bias, tropical forests still have higher beta-diversity than temperate, contributing to the latitudinal gradient of species richness. This supports the hypothesis of tighter species packing and larger niche space in tropical forests while demonstrating the importance of local processes in controlling beta-diversity.

scholarly journals Perception of the Müller–Lyer illusion in guppies

2019 ◽  
Vol 66 (2) ◽  
pp. 205-213 ◽  
Author(s):  
Maria Santacà ◽  
Christian Agrillo
Keyword(s):  
Teleost Fish ◽  
Poecilia Reticulata ◽  
Animal Species ◽  
Relative Length ◽  
Spatial Arrangement ◽  
Learning Criterion ◽  
Size Estimation ◽  
Lyer Illusion ◽  
Overall Performance ◽  
Discriminative Cue

Abstract The Müller–Lyer illusion is a well-known distortion illusion that occurs when the spatial arrangement of inducers (i.e., inwards- or outwards-pointing arrowheads) influences a line’s perceived relative length. To date, this illusion has been reported in several animal species but only in 1 teleost fish (i.e., redtail splitfins Xenotoca eiseni), although teleost fish represent approximately 50% of vertebrate diversity. We investigated the perception of this illusion in another teleost fish: guppies Poecilia reticulata, a species that diverged from the redtail splitfin 65 million years ago. The guppies were trained to select the longer between 2 lines; after meeting the learning criterion, illusory trials were presented. Control trials were also arranged to exclude the possibility that their choices were based on potential spatial biases that relate to the illusory pattern. The guppies’ overall performance indicated that they were susceptible to the Müller–Lyer illusion, perceiving the line with the inwards-pointing arrowheads as longer. The performance in the control trials excluded the possibility that the subjects used the physical differences between the 2 figures as the discriminative cue in the illusory trials. Our study suggests that sensibility to the Müller–Lyer illusion could be widespread across teleost fish and reinforces the idea that the perceptual mechanisms underlying size estimation might be similar across vertebrates.

scholarly journals Quantification of habitat fragmentation reveals extinction risk in terrestrial mammals

2017 ◽  
Vol 114 (29) ◽  
pp. 7635-7640 ◽  
Author(s):  
Kevin R. Crooks ◽  
Christopher L. Burdett ◽  
David M. Theobald ◽  
Sarah R. B. King ◽  
Moreno Di Marco ◽  
...  
Keyword(s):  
Habitat Fragmentation ◽  
Extinction Risk ◽  
Threat Assessment ◽  
Risk Assessments ◽  
Phylogenetic Comparative Methods ◽  
Terrestrial Mammals ◽  
Geographic Range Size ◽  
Mammal Conservation ◽  
Primary Driver ◽  
Animal Taxon

Although habitat fragmentation is often assumed to be a primary driver of extinction, global patterns of fragmentation and its relationship to extinction risk have not been consistently quantified for any major animal taxon. We developed high-resolution habitat fragmentation models and used phylogenetic comparative methods to quantify the effects of habitat fragmentation on the world’s terrestrial mammals, including 4,018 species across 26 taxonomic Orders. Results demonstrate that species with more fragmentation are at greater risk of extinction, even after accounting for the effects of key macroecological predictors, such as body size and geographic range size. Species with higher fragmentation had smaller ranges and a lower proportion of high-suitability habitat within their range, and most high-suitability habitat occurred outside of protected areas, further elevating extinction risk. Our models provide a quantitative evaluation of extinction risk assessments for species, allow for identification of emerging threats in species not classified as threatened, and provide maps of global hotspots of fragmentation for the world’s terrestrial mammals. Quantification of habitat fragmentation will help guide threat assessment and strategic priorities for global mammal conservation.

Systematics of new subsocial and solitary Australasian Anelosimus species (Araneae:Theridiidae)

2012 ◽  
Vol 26 (1) ◽  
pp. 1 ◽  
Author(s):  
Ingi Agnarsson
Keyword(s):  
Phylogenetic Analysis ◽  
Papua New Guinea ◽  
Tropical Forests ◽  
Social Evolution ◽  
New Guinea ◽  
High Latitudes ◽  
Unknown Species ◽  
The World ◽  
Solitary Species ◽  
Ecological Pattern

Species of the cobweb spider genus Anelosimus range from solitary to subsocial to social, and sociality has evolved repeatedly within the genus. Thus, this genus allows studies of the traits that play a role in social evolution. However, taxonomic knowledge of Anelosimus is geographically narrow and nearly all sociobiological studies have been done in the Americas. Only one behaviourally unknown species has been described from all of Australasia. Here, I describe seven new Anelosimus from Papua New Guinea (Anelosimus potmosbi, sp. nov., Anelosimus pomio, sp. nov., Anelosimus eidur, sp. nov. and Anelosimus luckyi, sp. nov.), Bali (Anelosimus bali, sp. nov.), Australia (Anelosimus pratchetti, sp. nov.) and an unknown locality (Anelosimus terraincognita, sp. nov.), ranging from solitary to subsocial. A phylogenetic analysis supports the inclusion of these species in Anelosimus, and suggests that solitary Papuan species represent a second reversal from subsocial behaviour. Both solitary species inhabit the beachfront, a habitat that appears not to be conducive to social behaviour in spiders. Subsocial species, as in other parts of the world, are found in montane tropical forests of Papua New Guinea, and at relatively high latitudes in Australia. Thus, a global ecological pattern of sociality in Anelosimus is emerging as taxonomic, phylogenetic and ethological knowledge extends beyond the Americas.

scholarly journals Habitat fragmentation, biodiversity loss and the risk of novel infectious disease emergence

2018 ◽  
Vol 15 (149) ◽  
pp. 20180403 ◽  
Author(s):  
David A. Wilkinson ◽  
Jonathan C. Marshall ◽  
Nigel P. French ◽  
David T. S. Hayman
Keyword(s):  
Habitat Fragmentation ◽  
Tropical Forests ◽  
Biodiversity Loss ◽  
Mitigation Measures ◽  
Infectious Agents ◽  
Disease Emergence ◽  
Zoonotic Infections ◽  
Species Area ◽  
Risk Areas ◽  
Species Area Relationship

The number of microbes on Earth may be 10 30 , exceeding all other diversity. A small number of these can infect people and cause disease. The diversity of parasitic organisms likely correlates with the hosts they live in and the number mammal hosts for zoonotic infections increases with species richness among mammalian orders. Thus, while habitat loss and fragmentation may reduce species diversity, the habitat encroachment by people into species-rich areas may increase the exposure of people to novel infectious agents from wildlife. Here, we present a theoretical framework that exploits the species–area relationship to link the exposure of people to novel infections with habitat biodiversity. We model changes in human exposure to microbes through defined classes of habitat fragmentation and predict that increased habitat division intrinsically increases the hazard from microbes for all modelled biological systems. We apply our model to African tropical forests as an example. Our results suggest that it is possible to identify high-risk areas for the mitigation and surveillance of novel disease emergence and that mitigation measures may reduce this risk while conserving biodiversity.

scholarly journals Persistent collapse of biomass in Amazonian forest edges following deforestation leads to unaccounted carbon losses

2020 ◽  
Vol 6 (40) ◽  
pp. eaaz8360 ◽  
Author(s):  
Celso H. L. Silva Junior ◽  
Luiz E. O. C. Aragão ◽  
Liana O. Anderson ◽  
Marisa G. Fonseca ◽  
Yosio E. Shimabukuro ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Tropical Forests ◽  
Forest Fragmentation ◽  
Edge Effect ◽  
Carbon Emissions ◽  
Forest Edges ◽  
Amazonian Forest ◽  
Primary Driver ◽  
The Tropics ◽  
Carbon Losses

Deforestation is the primary driver of carbon losses in tropical forests, but it does not operate alone. Forest fragmentation, a resulting feature of the deforestation process, promotes indirect carbon losses induced by edge effect. This process is not implicitly considered by policies for reducing carbon emissions in the tropics. Here, we used a remote sensing approach to estimate carbon losses driven by edge effect in Amazonia over the 2001 to 2015 period. We found that carbon losses associated with edge effect (947 Tg C) corresponded to one-third of losses from deforestation (2592 Tg C). Despite a notable negative trend of 7 Tg C year−1 in carbon losses from deforestation, the carbon losses from edge effect remained unchanged, with an average of 63 ± 8 Tg C year−1. Carbon losses caused by edge effect is thus an additional unquantified flux that can counteract carbon emissions avoided by reducing deforestation, compromising the Paris Agreement’s bold targets.

scholarly journals Species packing and the latitudinal gradient in beta-diversity

2021 ◽  
Vol 288 (1948) ◽  
Author(s):  
Ke Cao ◽  
Richard Condit ◽  
Xiangcheng Mi ◽  
Lei Chen ◽  
Haibao Ren ◽  
...  
Keyword(s):  
Species Richness ◽  
Tropical Forests ◽  
Beta Diversity ◽  
Environmental Gradient ◽  
Latitudinal Gradient ◽  
Small Samples ◽  
Gamma Diversity ◽  
Species Packing ◽  
High Gamma ◽  
Species Richness Gradient

The decline in species richness at higher latitudes is among the most fundamental patterns in ecology. Whether changes in species composition across space (beta-diversity) contribute to this gradient of overall species richness (gamma-diversity) remains hotly debated. Previous studies that failed to resolve the issue suffered from a well-known tendency for small samples in areas with high gamma-diversity to have inflated measures of beta-diversity. Here, we provide a novel analytical test, using beta-diversity metrics that correct the gamma-diversity and sampling biases, to compare beta-diversity and species packing across a latitudinal gradient in tree species richness of 21 large forest plots along a large environmental gradient in East Asia. We demonstrate that after accounting for topography and correcting the gamma-diversity bias, tropical forests still have higher beta-diversity than temperate analogues. This suggests that beta-diversity contributes to the latitudinal species richness gradient as a component of gamma-diversity. Moreover, both niche specialization and niche marginality (a measure of niche spacing along an environmental gradient) also increase towards the equator, after controlling for the effect of topographical heterogeneity. This supports the joint importance of tighter species packing and larger niche space in tropical forests while also demonstrating the importance of local processes in controlling beta-diversity.

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