共查询到20条相似文献，搜索用时 15 毫秒
1.
Luis F. De Len Diana M. T. Sharpe Kiyoko M. Gotanda Joost A. M. Raeymaekers Jaime A. Chaves Andrew P. Hendry Jeffrey Podos 《Evolutionary Applications》2019,12(7):1329-1343
Urbanization is influencing patterns of biological evolution in ways that are only beginning to be explored. One potential effect of urbanization is in modifying ecological resource distributions that underlie niche differences and that thus promote and maintain species diversification. Few studies have assessed such modifications, or their potential evolutionary consequences, in the context of ongoing adaptive radiation. We study this effect in Darwin's finches on the Galápagos Islands, by quantifying feeding preferences and diet niche partitioning across sites with different degrees of urbanization. We found higher finch density in urban sites and that feeding preferences and diets at urban sites skew heavily toward human food items. Furthermore, we show that finches at urban sites appear to be accustomed to the presence of people, compared with birds at sites with few people. In addition, we found that human behavior via the tendency to feed birds at non‐urban but tourist sites is likely an important driver of finch preferences for human foods. Site differences in diet and feeding behavior have resulted in larger niche breadth within finch species and wider niche overlap between species at the urban sites. Both factors effectively minimize niche differences that would otherwise facilitate interspecies coexistence. These findings suggest that both human behavior and ongoing urbanization in Galápagos are starting to erode ecological differences that promote and maintain adaptive radiation in Darwin's finches. Smoothing of adaptive landscapes underlying diversification represents a potentially important yet underappreciated consequence of urbanization. Overall, our findings accentuate the fragility of the initial stages of adaptive radiation in Darwin's finches and raise concerns about the fate of the Galápagos ecosystems in the face of increasing urbanization. 相似文献
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Beak shape in Darwin's ground finches (Geospiza) is emblematic of natural selection and adaptive radiation, yet our understanding of the genetic basis of beak shape variation, and thus the genetic target of natural selection, is still evolving. Here we reveal the genomic architecture of beak shape variation using genomewide comparisons of four closely related and hybridizing species across 13 islands subject to parallel natural selection. Pairwise contrasts among species were used to identify a large number of genomic loci that are consistently related to species differences across a complex landscape. These loci are associated with hundreds of genes that have enriched GO categories significantly associated with development. One genomic region of particular interest is a section of Chromosome 1A with many candidate genes and increased linkage. The distinct, pointed beak shape of the cactus finch is linked to an excess of intermediate frequency alleles and increased heterozygosity in significant SNPs, but not across the rest of the genome. Alleles associated with pointier beaks among species were associated with pointier‐beaked populations within each species, thus establishing a common basis for natural selection, species divergence and adaptive radiation. The adaptive genomic landscape for Darwin's finches mirrors theoretical expectations based on morphological variation. The implication that a large number of genes are actively maintained to facilitate beak variation across parallel populations with documented interspecies admixture challenges our understanding of evolutionary processes in the wild. 相似文献
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Dietary differences between hamlet Hypoplectrus spp. colour morphs were examined in fishes from Puerto Rico, U.S. Virgin Islands, Curacao, Honduras and Belize. Hamlet diet across all countries was characterized by large overlap between most colour morphs in both the proportion and numbers of dietary items consumed, although some differences between morphs were apparent. Indigo hamlets Hypoplectrus indigo were the only morph to consume fishes (blue chromis Chromis cyanea and sunshinefish Chromis insolata ) almost exclusively. The sympatric occurrence of other ecologically indistinguishable colour morphs, however, suggests that divergent ecological selection alone cannot explain population divergence in hamlets. Geographical variation in diet was also observed within black Hypoplectrus nigricans and yellowtail Hypoplectrus chlorurus hamlets which may reflect geographical differences in prey availability or differences in prey choice. 相似文献
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Beak size and shape in Darwin's finches have traditionally been quantified using a few univariate measurements (length, depth, width). Here we show the improved inferential resolution of geometric morphometric methods, as applied to three hierarchical levels: (i) among seven species on Santa Cruz Island, (ii) among different sites on Santa Cruz for a single species (Geospiza fortis), and (iii) between large and small beak size morphs of G. fortis at one site (El Garrapatero). Our results support previous studies in finding an axis of shape variation (long/shallow/pointy vs. short/deep/blunt) that separates many of the species. We also detect additional differences among species in the relative sizes and positions of the upper and lower mandibles and in curvature of the mandibles. Small-scale, but potentially relevant, shape variation was also detected among G. fortis from different sites and between sympatric beak size morphs. These results suggest that adaptation to different resources might contribute to diversification on a single island. 相似文献
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Rachael Y. Dudaniec Zohar Pasternak Edouard Jurkevitch Renee J. Smith Charlotte E. Causton Maria Piedad Lincango Shanan S. Tobe James G. Mitchell Sonia Kleindorfer Boaz Yuval 《Molecular ecology》2017,26(18):4644-4656
The composition and diversity of bacteria forming the microbiome of parasitic organisms have implications for differential host pathogenicity and host–parasite co‐evolutionary interactions. The microbiome of pathogens can therefore have consequences that are relevant for managing disease prevalence and impact on affected hosts. Here, we investigate the microbiome of an invasive parasitic fly Philornis downsi, recently introduced to the Galápagos Islands, where it poses extinction threat to Darwin's finches and other land birds. Larvae infest nests of Darwin's finches and consume blood and tissue of developing nestlings, and have severe mortality impacts. Using 16s rRNA sequencing data, we characterize the bacterial microbiota associated with P. downsi adults and larvae sourced from four finch host species, inhabiting two islands and representing two ecologically distinct groups. We show that larval and adult microbiomes are dominated by the phyla Proteobacteria and Firmicutes, which significantly differ between life stages in their distributions. Additionally, bacterial community structure significantly differed between larvae retrieved from strictly insectivorous warbler finches (Certhidea olivacea) and those parasitizing hosts with broader dietary preferences (ground and tree finches, Geospiza and Camarhynchus spp., respectively). Finally, we found no spatial effects on the larval microbiome, as larvae feeding on the same host (ground finches) harboured similar microbiomes across islands. Our results suggest that the microbiome of P. downsi changes during its development, according to dietary composition or nutritional needs, and is significantly affected by host‐related factors during the larval stage. Unravelling the ecological significance of bacteria for this parasite will contribute to the development of novel, effective control strategies. 相似文献
6.
Federico Luebert Pit Jacobs Hartmut H. Hilger Ludo A. H. Muller 《Ecology and evolution》2014,4(3):266-275
The genetic structure of populations of closely related, sympatric species may hold the signature of the geographical mode of the speciation process. In fully allopatric speciation, it is expected that genetic differentiation between species is homogeneously distributed across the genome. In nonallopatric speciation, the genomes may remain undifferentiated to a large extent. In this article, we analyzed the genetic structure of five sympatric species from the plant genus Heliotropium in the Atacama Desert. We used amplified fragment length polymorphisms (AFLPs) to characterize the genetic structure of these species and evaluate their genetic differentiation as well as the number of loci subject to positive selection using divergence outlier analysis (DOA). The five species form distinguishable groups in the genetic space, with zones of overlap, indicating that they are possibly not completely isolated. Among‐species differentiation accounts for 35% of the total genetic differentiation (FST = 0.35), and FST between species pairs is positively correlated with phylogenetic distance. DOA suggests that few loci are subject to positive selection, which is in line with a scenario of nonallopatric speciation. These results support the idea that sympatric species of Heliotropium sect. Cochranea are under an ongoing speciation process, characterized by a fluctuation of population ranges in response to pulses of arid and humid periods during Quaternary times. 相似文献
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《Insect Conservation and Diversity》2017,10(3):193-199
- The survival of parasites is threatened directly by environmental alteration and indirectly by all the threats acting upon their hosts, facing coextinction.
- The fate of Darwin's finches and their native ectoparasites in the Galápagos Islands is uncertain because of an introduced avian parasitic fly, Philornis downsi, which could potentially drive them to extinction.
- We documented all known native ectoparasites of Darwin's finches. Thirteen species have been found: nine feather mites, three feather lice and one nest mite. No ticks or fleas have been recorded from them yet.
- Management options being considered to control P. downsi include the use of the insecticide permethrin in bird nests which would not only kill the invasive fly larvae but the birds’ native ectoparasites too.
- Parasites should be targeted for conservation in a manner equal to that of their hosts. We recommend steps to consider if permethrin‐treated cotton stations are to be deployed in the Galápagos archipelago to manage P. downsi.
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Evolutionary radiations are among the most intriguing natural phenomena. Sigmodontine rodents form a megadiverse group for which doubts exist about the adaptive or non‐adaptive nature of its radiation. We analysed whether or not the rates of diversification of species of Sigmodontinae are related to the rates of diversification of the climatic niches occupied by the species. Our results show a clear association between niche diversification and speciation processes. However, this association is linked to recent and independent processes of diversification in sigmodontines, as opposed to an early link that would indicate a niche‐filling consistent with an adaptive radiation of the subfamily. 相似文献
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De León LF Raeymaekers JA Bermingham E Podos J Herrel A Hendry AP 《Evolution; international journal of organic evolution》2011,65(8):2258-2272
Humans are an increasingly common influence on the evolution of natural populations. Potential arenas of influence include altered evolutionary trajectories within populations and modifications of the process of divergence among populations. We consider this second arena in the medium ground finch (Geospiza fortis) on Santa Cruz Island, Galápagos, Ecuador. Our study compared the G. fortis population at a relatively undisturbed site, El Garrapatero, to the population at a severely disturbed site, Academy Bay, which is immediately adjacent to the town of Puerto Ayora. The El Garrapatero population currently shows beak size bimodality that is tied to assortative mating and disruptive selection, whereas the Academy Bay population was historically bimodal but has lost this property in conjunction with a dramatic increase in local human population density. We here evaluate potential ecological-adaptive drivers of the differences in modality by quantifying relationships between morphology (beak and head dimensions), functional performance (bite force), and environmental characteristics (diet). Our main finding is that associations among these variables are generally weaker at Academy Bay than at El Garrapatero, possibly because novel foods are used at the former site irrespective of individual morphology and performance. These results are consistent with the hypothesis that the rugged adaptive landscapes promoting and maintaining diversification in nature can be smoothed by human activities, thus hindering ongoing adaptive radiation. 相似文献
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Parasite specialization on one or a few host species leads to a reduction in the total number of available host individuals, which may decrease transmission. However, specialists are thought to be able to compensate by increased prevalence in the host population and increased success in each individual host. Here, we use variation in host breadth among a community of avian Haemosporida to investigate consequences of generalist and specialist strategies on prevalence across hosts. We show that specialist parasites are more prevalent than generalist parasites in host populations that are shared between them. Moreover, the total number of infections of generalist and specialist parasites within the study area did not vary significantly with host breadth. This suggests that specialists can infect a similar number of host individuals as generalists, thus compensating for a reduction in host availability by achieving higher prevalence in a single host species. Specialist parasites also tended to infect older hosts, whereas infections by generalists were biased towards younger hosts. We suggest that this reflects different abilities of generalists and specialists to persist in hosts following infection. Higher abundance and increased persistence in hosts suggest that specialists are more effective parasites than generalists, supporting the existence of a trade‐off between host breadth and average host use among these parasites. 相似文献
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Angela Nava‐Bolaos Rosa A. Snchez‐Guilln Maren Wellenreuther Jesús Muoz Mnica Torres‐Pachn Rodolfo Novelo‐Gutirrez Alex Crdoba‐Aguilar 《Insect Conservation and Diversity》2019,12(5):427-436
- Climate change is a key stressor for species. Two major consequences of climate‐induced range shifts are the formation of new areas of geographic overlap (i.e. sympatry) and an increased probability of hybridisation in the de novo created contact zones.
- One method to effectively quantify the potential of hybridisation is to integrate ecological niche modelling and the propensity to hybridisation based on genetic divergence. In this paper, we have applied this methodology to predict hybridisation outcomes following different scenarios of climate change in 30 species of Argia damselflies.
- We (i) investigated how climate change may affect species’ distributions; (ii) quantified if changed distributions generate new areas of sympatry between species; (iii) calculated the propensity to hybridise based on genetic divergence between species; and (iv) integrated these data to predict the future potential of species to hybridise.
- We found that the distribution of 29 of the 30 species was affected by a change in climate which led to a general increase in sympatric overlap among species. The degree of genetic divergence among the 108 species’ combinations ranged from 0.06% to 0.36%. Based on the sympatric overlap and genetic divergence, it can be predicted that 97 of the species pairs are likely to hybridise in the future.
- Our results are useful to forecast how highly diverse and closely related groups, such as Argia damselflies, may respond to a change in climate and how this can impact the potential of species mixing under a scenario of increased global warming.
15.
Peter R. Grant B. Rosemary Grant 《Evolution; international journal of organic evolution》1995,49(2):241-251
Microevolution of quantitative traits in the wild can be predicted from a knowledge of selection and genetic parameters. Testing the predictions requires measurement of the offspring of the selected group, a requirement that is difficult to meet. We present the results of a study of Darwin's finches on the Galápagos island of Daphne Major where this requirement is met. The study demonstrates microevolutionary consequences of natural selection. 相似文献
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Baoyan Liu Per Alström Urban Olsson Jon Fjeldså Qing Quan Kees C. S. Roselaar Takema Saitoh Cheng‐te Yao Yan Hao Wenjuan Wang Yanhua Qu Fumin Lei 《Ecology and evolution》2017,7(16):6346-6357
Our objective was to elucidate the biogeography and speciation patterns in an entire avian family, which shows a complex pattern of overlapping and nonoverlapping geographical distributions, and much variation in plumage, but less in size and structure. We estimated the phylogeny and divergence times for all of the world's species of Prunella based on multiple genetic loci, and analyzed morphometric divergence and biogeographical history. The common ancestor of Prunella was present in the Sino‐Himalayan Mountains or these mountains and Central Asia–Mongolia more than 9 million years ago (mya), but a burst of speciations took place during the mid‐Pliocene to early Pleistocene. The relationships among the six primary lineages resulting from that differentiation are unresolved, probably because of the rapid radiation. A general increase in sympatry with increasing time since divergence is evident. With one exception, species in clades younger than c. 3.7 my are allopatric. Species that are widely sympatric, including the most recently diverged (2.4 mya) sympatric sisters, are generally more divergent in size/structure than allo‐/parapatric close relatives. The distributional pattern and inferred ages suggest divergence in allopatry and substantial waiting time until secondary contact, likely due to competitive exclusion. All sympatrically breeding species are ecologically segregated, as suggested by differences in size/structure and habitat. Colonizations of new areas were facilitated during glacial periods, followed by fragmentation during interglacials—contrary to the usual view that glacial periods resulted mainly in fragmentations. 相似文献
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Yueyun Zhang Chongtao Chen Li Li Chengjian Zhao Weicai Chen Yong Huang 《Ecology and evolution》2014,4(17):3383-3394
The black‐spotted tokay and the red‐spotted tokay are morphologically distinct and have largely allopatric distributions. The black‐spotted tokay is characterized by a small body size and dark skin with sundry spots, while the red‐spotted tokay has a relatively large body size and red spots. Based on morphological, karyotypic, genetic, and distribution differences, recent studies suggested their species status; however, their classifications remain controversial, and additional data such as ecological niches are necessary to establish firm hypotheses regarding their taxonomic status. We reconstructed their ecological niches models using climatic and geographic data. We then performed niche similarity tests (niche identity and background tests) and point‐based analyses to explore whether ecological differentiation has occurred, and whether such differences are sufficient to explain the maintenance of their separate segments of environmental ranges. We found that both niche models of the black‐ and the red‐spotted tokay had a good fit and a robust performance, as indicated by the high area under the curve (AUC) values (“black” = 0.982, SD = ± 0.002, “red” = 0.966 ± 0.02). Significant ecological differentiation across the entire geographic range was found, indicating that the involvement of ecological differentiation is important for species differentiation. Divergence along the environmental axes is highly associated with climatic conditions, with isothermality being important for the “black” form, while temperature seasonality, precipitation of warmest quarter, and annual temperature range together being important for the “red” form. These factors are likely important factors in niche differentiation between the two forms, which result in morphological replacement. Overall, beside morphological and genetic differentiation information, our results contribute to additional insights into taxonomic distinction and niche differentiation between the black‐ and the red‐spotted tokay. 相似文献
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Lauren K. Common Jody A. O&#x;Connor Rachael Y. Dudaniec Katharina J. Peters Sonia Kleindorfer 《Journal of evolutionary biology》2020,33(4):524-533
Fecundity selection is a critical component of fitness and a major driver of adaptive evolution. Trade‐offs between parasite mortality and host resources are likely to impose a selection pressure on parasite fecundity, but this is little studied in natural systems. The ‘fecundity advantage hypothesis’ predicts female‐biased sexual size dimorphism whereby larger females produce more offspring. Parasitic insects are useful for exploring the interplay between host resource availability and parasite fecundity, because female body size is a reliable proxy for fecundity in insects. Here we explore temporal changes in body size in the myiasis‐causing parasite Philornis downsi (Diptera: Muscidae) on the Galápagos Islands under conditions of earlier in‐nest host mortality. We aim to investigate the effects of decreasing host resources on parasite body size and fecundity. Across a 12‐year period, we observed a mean of c. 17% P. downsi mortality in host nests with 55 ± 6.2% host mortality and a trend of c. 66% higher host mortality throughout the study period. Using specimens from 116 Darwin's finch nests (Passeriformes: Thraupidae) and 114 traps, we found that over time, P. downsi pupae mass decreased by c. 32%, and male (c. 6%) and female adult size (c. 11%) decreased. Notably, females had c. 26% smaller abdomens in later years, and female abdomen size was correlated with number of eggs. Our findings imply natural selection for faster P. downsi pupation and consequently smaller body size and lower parasite fecundity in this newly evolving host–parasite system. 相似文献
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