scholarly journals Adaptive introgression during environmental change can weaken reproductive isolation

2019 ◽  
Author(s):  
Gregory L. Owens ◽  
Kieran Samuk
Keyword(s):  
Climate Change ◽  
Species Diversity ◽  
Reproductive Isolation ◽  
Genetic Architecture ◽  
Species Boundaries ◽  
Reproductive Barriers ◽  
Climatic Variable ◽  
Adaptive Introgression ◽  
Primary Mechanism ◽  
Reverse Speciation

AbstractAnthropogenic climate change is an urgent threat to species diversity. One aspect of this threat is the collapse of species reproductive barriers through increased hybridization. The primary mechanism for this collapse is thought to be the weakening of ecologically-mediated reproductive barriers, as demonstrated in many cases of “reverse speciation” . Here, we expand on this idea and show that adaptive introgression between species adapting to a shared, moving climatic optimum can readily weaken any reproductive barrier, including those that are completely independent of the climatic variable. Using genetically explicit forward-time simulations, we show that genetic linkage between alleles conferring adaptation to a changing climate and alleles conferring reproductive isolation can lead to adaptive introgression facilitating the homogenization of reproductive isolation alleles. This effect causes the decay of species boundaries across a broad and biologically-realistic parameter space. We explore how the magnitude of this effect depends upon the rate of climate change, the genetic architecture of adaptation, the initial degree of reproductive isolation and the mutation rate. These results highlight a previously unexplored effect of rapid climate change on species diversity.

Hybrid Zones and the Genetic Architecture of a Barrier to Gene Flow Between Two Sunflower Species

Genetics ◽  
1999 ◽  
Vol 152 (2) ◽  
pp. 713-727 ◽  
Author(s):  
Loren H Rieseberg ◽  
Jeannette Whitton ◽  
Keith Gardner
Keyword(s):  
Genetic Study ◽  
Genetic Architecture ◽  
Chromosomal Rearrangements ◽  
Pollen Sterility ◽  
Model Organisms ◽  
Hybrid Zones ◽  
Reproductive Barriers ◽  
Natural Hybrid ◽  
Generation Times ◽  
Helianthus Petiolaris

Abstract Genetic analyses of reproductive barriers represent one of the few methods by which theories of speciation can be tested. However, genetic study is often restricted to model organisms that have short generation times and are easily propagated in the laboratory. Replicate hybrid zones with a diversity of recombinant genotypes of varying age offer increased resolution for genetic mapping experiments and expand the pool of organisms amenable to genetic study. Using 88 markers distributed across 17 chromosomes, we analyze the introgression of chromosomal segments of Helianthus petiolaris into H. annuus in three natural hybrid zones. Introgression was significantly reduced relative to neutral expectations for 26 chromosomal segments, suggesting that each segment contains one or more factors that contribute to isolation. Pollen sterility is significantly associated with 16 of these 26 segments, providing a straightforward explanation of why this subset of blocks is disadvantageous in hybrids. In addition, comparison of rates of introgression across colinear vs. rearranged chromosomes indicates that close to 50% of the barrier to introgression is due to chromosomal rearrangements. These results demonstrate the utility of hybrid zones for identifying factors contributing to isolation and verify the prediction of increased resolution relative to controlled crosses.

Introgression between non-sister species of honeyeaters (Aves: Meliphagidae) several million years after speciation

2019 ◽  
Vol 128 (3) ◽  
pp. 583-591
Author(s):  
Leo Joseph ◽  
Alex Drew ◽  
Ian J Mason ◽  
Jeffrey L Peters
Keyword(s):  
Gene Flow ◽  
Reproductive Isolation ◽  
Sex Chromosomes ◽  
Common Ancestor ◽  
Sister Species ◽  
Species Boundaries ◽  
North Eastern ◽  
The City

Abstract We reassessed whether two parapatric non-sister Australian honeyeater species (Aves: Meliphagidae), varied and mangrove honeyeaters (Gavicalis versicolor and G. fasciogularis, respectively), that diverged from a common ancestor c. 2.5 Mya intergrade in the Townsville area of north-eastern Queensland. Consistent with a previous specimen-based study, by using genomics methods we show one-way gene flow for autosomal but not Z-linked markers from varied into mangrove honeyeaters. Introgression barely extends south of the area of parapatry in and around the city of Townsville. While demonstrating the long-term porosity of species boundaries over several million years, our data also suggest a clear role of sex chromosomes in maintaining reproductive isolation.

scholarly journals The Use of Homegarden Agroforestry Systems for Climate Change Mitigation in Lowlands of Southern Tigray, Northern Ethiopia

2019 ◽  
pp. 1-13
Author(s):  
Gebru Eyasu Siyum ◽  
Tuemay Tassew
Keyword(s):  
Climate Change ◽  
Species Diversity ◽  
Climate Change Mitigation ◽  
Woody Species ◽  
Agroforestry Systems ◽  
Carbon Stocks ◽  
Land Uses ◽  
Woody Species Diversity ◽  
Soil Carbon Stocks ◽  
Change Mitigation

Mitigation of climate change is one of the major environmental challenges facing the globe. In this context, homegarden agroforestry systems (HGAFs) have large potential for climate change mitigation. Therefore, this study was initiated to estimate the biomass and soil carbon stocks of HGAFs in relation to adjacent Natural Forest (NF). It also analyzed the relationship between woody species diversity, evenness and richness with biomass and soil carbon stocks. Three sites were purposely selected on the basis of the presence of HGAFs and NF adjacent to each other. Random sampling was used to select representative homegardens from the study population. In NF, a systematic sampling technique was employed. A total of 60 plots with a size of 10 m x 20 m were used to collect vegetation and soil data in both land uses. Soil samples were collected from each plot of the samples laid for vegetation sampling. Accordingly, 120 composite and 120 undisturbed soil samples from 0-30 cm and 30-60 cm soil depths were collected for soil organic carbon (SOC) and bulk density analysis respectively. Biomass estimation for each woody species was analyzed by using appropriate allometric equations. The result showed that the total amount of carbon stocks was 148.32±35.76 tons ha-1 and 157.27±51.61 tons ha-1 in HGAFs and adjacent NF respectively which did not vary significantly between the two studied land uses (P > 0.05). The finding also shows a positive but non-significant (P>0.05) relationship between carbon stocks and woody species diversity, richness, and evenness. Specifically, in NF lands, woody species diversity with SOC (r=0.36) and in HGAFs species richness with biomass carbon (r=0.39) was correlated positively and significantly (P=0.05). We concluded that HGAFs have the same potential as the NF for carbon stock accumulation and to counteract the loss of biomass.

scholarly journals Balancing selection and introgression of newt immune-response genes

2018 ◽  
Vol 285 (1884) ◽  
pp. 20180819 ◽  
Author(s):  
Anna Fijarczyk ◽  
Katarzyna Dudek ◽  
Marta Niedzicka ◽  
Wiesław Babik
Keyword(s):  
Gene Flow ◽  
Genetic Variants ◽  
Balancing Selection ◽  
Species Boundaries ◽  
Adaptive Introgression ◽  
Interspecific Introgression ◽  
Differential Gene ◽  
And Migration ◽  
Relevant Variation ◽  
Novel Allele

The importance of interspecific introgression as a source of adaptive variation is increasingly recognized. Theory predicts that beneficial genetic variants cross species boundaries easily even when interspecific hybridization is rare and gene flow is strongly constrained throughout the genome. However, it remains unclear whether certain classes of genes are particularly prone to adaptive introgression. Genes affected by balancing selection (BS) may constitute such a class, because forms of BS that favour novel, initially rare alleles, should facilitate introgression. We tested this hypothesis in hybridizing newts by comparing 13 genes with signatures of BS, in particular an excess of common non-synonymous polymorphisms, to the genomic background (154 genes). Parapatric hybridizing taxa were less differentiated in BS candidate genes than more closely related allopatric lineages, while the opposite was observed in the control genes. Coalescent and forward simulations that explored neutral and BS scenarios under isolation and migration showed that processes other than differential gene flow are unlikely to account for this pattern. We conclude that BS, probably involving a form of novel allele advantage, promotes introgression. This mechanism may be a source of adaptively relevant variation in hybridizing species over prolonged periods.

Biodiversity, Distributions, and Extinction

2013 ◽  
Author(s):  
Eric Post
Keyword(s):  
Climate Change ◽  
Species Diversity ◽  
Time Scales ◽  
Upper And Lower Bounds ◽  
Ecosystem Goods And Services ◽  
Goods And Services ◽  
Local Diversity ◽  
Rapid Climate Change ◽  
The Subject ◽  
The Relationship

This chapter examines the relationship between species diversity and ecosystem function and stability. This subject is currently one of the most intensely studied topics in ecology. It is also of paramount importance in the study of the ecological consequences of climate change, most probably because of its obvious relevance to ecosystem goods and services. More classically, however, the subject of biodiversity response to climate change relates to what factors set limits to the upper and lower bounds of species diversity and how those factors might be altered by rapid climate change. Of the two processes generating diversity—speciation and immigration—the latter obviously operates at shorter time scales and is likely to respond more immediately to climate change. Of the processes reducing local diversity—extinction and emigration—the latter is, again, likely to operate at shorter time scales, but both processes are likely to be influenced by climate change, although at potentially different timescales.

The response of the species diversity pattern of Populus to climate change in China

2020 ◽  
Vol 116 ◽  
pp. 102858 ◽  
Author(s):  
Fang Wang ◽  
Zhe Xiong ◽  
Xingang Dai ◽  
Yafei Li ◽  
Leibin Wang
Keyword(s):  
Climate Change ◽  
Species Diversity ◽  
Diversity Pattern
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