Adaptation to an invasive host is collapsing a native ecotype

2015 ◽  
Author(s):  
Meredith L Cenzer

Locally adapted populations are often used as model systems for the early stages of ecological speciation, but most of these young divergent lineages will never become complete species. While the collapse of incipient species is theoretically common, very few examples have been documented in nature. Here I show that soapberry bugs (Jadera haematoloma) have lost adaptations to their native host plant (Cardiospermum corindum) and are regionally specializing on an invasive host plant (Koelreuteria elegans), collapsing a classic and well-documented example of local adaptation. All populations that were adapted to the native host - including those still found on that host today - are now better adapted to the invasive in multiple phenotypes. Weak differentiation remains in two traits, suggesting that homogenization across the region is incomplete. This study highlights the potential for adaptation to invasive species to disrupt native communities by swamping adaptation to native conditions through maladaptive gene flow.

Author(s):  
Emmanuelle Jousselin ◽  
Marianne Elias

During the last two decades, ecological speciation has been a major research theme in evolutionary biology. Ecological speciation occurs when reproductive isolation between populations evolves as a result of niche differentiation. Phytophagous insects represent model systems for the study of this evolutionary process. The host-plants on which these insects feed and often spend parts of their life cycle constitute ideal agents of divergent selection for these organisms. Adaptation to feeding on different host-plant species can potentially lead to ecological specialization of populations and subsequent speciation. This process is thought to have given birth to the astonishing diversity of phytophagous insects and is often put forward in macroevolutionary scenarios of insect diversification. Consequently, numerous phylogenetic studies on phytophagous insects have aimed at testing whether speciation driven by host-plant adaptation is the main pathway for the diversification of the groups under investigation. The increasing availability of comprehensive and well-resolved phylogenies and the recent developments in phylogenetic comparative methods are offering an unprecedented opportunity to test hypotheses on insect diversification at a macroevolutionary scale, in a robust phylogenetic framework. Our purpose here is to review the contribution of phylogenetic analyses to investigate the importance of plant-mediated speciation in the diversification of phytophagous insects and to present suggestions for future developments in this field.


2016 ◽  
Author(s):  
M L Cenzer

AbstractNatural selection and phenotypic plasticity can both produce locally differentiated phenotypes, but novel environments or gene combinations can produce plasticity that works in opposition to adaptive change. The red-shouldered soapberry bug (Jadera haematoloma) was locally adapted to feed on the seeds of an introduced and a native host plant in Florida in the 1980s. By 2014, local differentiation was lost and replaced by phenotypically similar populations all adapted to the introduced host, likely as a result of gene flow. Here, I quantify the effects of these two host plants on individual performance, natural selection, and phenotypic plasticity. I find that the seed coat and seedpod of the native host have strong negative effects on juvenile survival and adult reproduction compared to the introduced host. I find support for the hypothesis that the seedpod is driving diversifying natural selection on beak length, which was previously locally adapted between hosts. I also find maladaptive plasticity induced by host plant: bugs develop beak lengths that are mismatched with the seedpod size of the host they are reared on. This plasticity may be the result of gene flow; hybrids in the 1990s showed the same pattern of maladaptive plasticity, and plasticity is stronger in the present in areas with high gene flow. Although ongoing natural selection has produced locally adapted genotypes in soapberry bugs, maladaptive plasticity has masked the phenotypic difference between populations in the field.


2017 ◽  
Author(s):  
Meredith L Cenzer

ABSTRACTWhether intraspecific interactions are facilitative or competitive may change across individual ontogeny. In plant-feeding insects, the direction of this interaction is likely to be mediated by host plant defenses. Here I conducted two experiments looking at the direct effect of a physical seed defense and the role of intraspecific facilitation in reducing the effects of that defense for juveniles. I first demonstrate that juveniles of the red-shouldered soapberry bug (Jadera haematoloma) are severely inhibited by the tough seed coat of their host plant, leading to high mortality early in development. Adults, in contrast, can create holes through which other individuals could potentially feed. I then manipulated whether or not seeds experienced adult feeding on two host plant species: a well-defended native host, balloon vine (Cardiospermum corindum) and a poorly defended introduced golden rain tree species (Koelreuteria elegans). I measured the effect of prior adult feeding on survival, development time, and final body size of soapberry bug juveniles. Survival in the first week of development was dramatically improved by prior adult feeding on both hosts. However, the benefits of prior adult feeding ceased after the first week of development and shifted to having a negative effect on performance. These results indicate that adults breaking through the seedcoat initially facilitate juveniles, but that this facilitation becomes competition as juveniles age.


Author(s):  
Emmanuelle Jousselin ◽  
Marianne Elias

During the last two decades, ecological speciation has been a major research theme in evolutionary biology. Ecological speciation occurs when reproductive isolation between populations evolves as a result of niche differentiation. Phytophagous insects represent model systems for the study of this evolutionary process. The host-plants on which these insects feed and often spend parts of their life cycle constitute ideal agents of divergent selection for these organisms. Adaptation to feeding on different host-plant species can potentially lead to ecological specialization of populations and subsequent speciation. This process is thought to have given birth to the astonishing diversity of phytophagous insects and is often put forward in macroevolutionary scenarios of insect diversification. Consequently, numerous phylogenetic studies on phytophagous insects have aimed at testing whether speciation driven by host-plant adaptation is the main pathway for the diversification of the groups under investigation. The increasing availability of comprehensive and well-resolved phylogenies and the recent developments in phylogenetic comparative methods are offering an unprecedented opportunity to test hypotheses on insect diversification at a macroevolutionary scale, in a robust phylogenetic framework. Our purpose here is to review the contribution of phylogenetic analyses to investigate the importance of plant-mediated speciation in the diversification of phytophagous insects and to present suggestions for future developments in this field.


Author(s):  
Emmanuelle Jousselin ◽  
Marianne Elias

During the last two decades, ecological speciation has been a major research theme in evolutionary biology. Ecological speciation occurs when reproductive isolation between populations evolves as a result of niche differentiation. Phytophagous insects represent model systems for the study of this evolutionary process. The host-plants on which these insects feed and often spend parts of their life cycle constitute ideal agents of divergent selection for these organisms. Adaptation to feeding on different host-plant species can potentially lead to ecological specialization of populations and subsequent speciation. This process is thought to have given birth to the astonishing diversity of phytophagous insects and is often put forward in macroevolutionary scenarios of insect diversification. Consequently, numerous phylogenetic studies on phytophagous insects have aimed at testing whether speciation driven by host-plant adaptation is the main pathway for the diversification of the groups under investigation. The increasing availability of comprehensive and well-resolved phylogenies and the recent developments in phylogenetic comparative methods are offering an unprecedented opportunity to test hypotheses on insect diversification at a macroevolutionary scale, in a robust phylogenetic framework. Our purpose here is to review the contribution of phylogenetic analyses to investigate the importance of plant-mediated speciation in the diversification of phytophagous insects and to present suggestions for future developments in this field.


2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Jeffrey L. Feder ◽  
Scott P. Egan ◽  
Andrew A. Forbes

Habitat choice is an important component of most models of ecologically based speciation, especially when population divergence occurs in the face of gene flow. We examine how organisms choose habitats and ask whether avoidance behavior plays an important role in habitat choice, focusing on host-specific phytophagous insects as model systems. We contend that when a component of habitat choice involves avoidance, there can be repercussions that can have consequences for enhancing the potential for specialization and postzygotic reproductive isolation and, hence, for ecological speciation. We discuss theoretical and empirical reasons for why avoidance behavior has not been fully recognized as a key element in habitat choice and ecological speciation. We present current evidence for habitat avoidance, emphasizing phytophagous insects, and new results for parasitoid wasps consistent with the avoidance hypothesis. We conclude by discussing avenues for further study, including other potential roles for avoidance behavior in speciation related to sexual selection and reinforcement.


Author(s):  
Emmanuelle Jousselin ◽  
Marianne Elias

During the last two decades, ecological speciation has been a major research theme in evolutionary biology. Ecological speciation occurs when reproductive isolation between populations evolves as a result of niche differentiation. Phytophagous insects represent model systems for the study of this evolutionary process. The host-plants on which these insects feed and often spend parts of their life cycle constitute ideal agents of divergent selection for these organisms. Adaptation to feeding on different host-plant species can potentially lead to ecological specialization of populations and subsequent speciation. This process is thought to have given birth to the astonishing diversity of phytophagous insects and is often put forward in macroevolutionary scenarios of insect diversification. Consequently, numerous phylogenetic studies on phytophagous insects have aimed at testing whether speciation driven by host-plant adaptation is the main pathway for the diversification of the groups under investigation. The increasing availability of comprehensive and well-resolved phylogenies and the recent developments in phylogenetic comparative methods are offering an unprecedented opportunity to test hypotheses on insect diversification at a macroevolutionary scale, in a robust phylogenetic framework. Our purpose here is to review the contribution of phylogenetic analyses to investigate the importance of plant-mediated speciation in the diversification of phytophagous insects and to present suggestions for future developments in this field.


BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Huai-Jun Xue ◽  
Yi-Wei Niu ◽  
Kari A. Segraves ◽  
Rui-E Nie ◽  
Ya-Jing Hao ◽  
...  

Abstract Background Altica (Coleoptera: Chrysomelidae) is a highly diverse and taxonomically challenging flea beetle genus that has been used to address questions related to host plant specialization, reproductive isolation, and ecological speciation. To further evolutionary studies in this interesting group, here we present a draft genome of a representative specialist, Altica viridicyanea, the first Alticinae genome reported thus far. Results The genome is 864.8 Mb and consists of 4490 scaffolds with a N50 size of 557 kb, which covered 98.6% complete and 0.4% partial insect Benchmarking Universal Single-Copy Orthologs. Repetitive sequences accounted for 62.9% of the assembly, and a total of 17,730 protein-coding gene models and 2462 non-coding RNA models were predicted. To provide insight into host plant specialization of this monophagous species, we examined the key gene families involved in chemosensation, detoxification of plant secondary chemistry, and plant cell wall-degradation. Conclusions The genome assembled in this work provides an important resource for further studies on host plant adaptation and functionally affiliated genes. Moreover, this work also opens the way for comparative genomics studies among closely related Altica species, which may provide insight into the molecular evolutionary processes that occur during ecological speciation.


2017 ◽  
Vol 1 (9) ◽  
pp. 1407-1410 ◽  
Author(s):  
Staffan Jacob ◽  
Delphine Legrand ◽  
Alexis S. Chaine ◽  
Dries Bonte ◽  
Nicolas Schtickzelle ◽  
...  

2011 ◽  
Vol 2011 ◽  
pp. 1-15 ◽  
Author(s):  
Aneil F. Agrawal ◽  
Jeffrey L. Feder ◽  
Patrik Nosil

The evolution of intrinsic postmating isolation has received much attention, both historically and in recent studies of speciation genes. Intrinsic isolation often stems from between-locus genetic incompatibilities, where alleles that function well within species are incompatible with one another when brought together in the genome of a hybrid. It can be difficult for such incompatibilities to originate when populations diverge with gene flow, because deleterious genotypic combinations will be created and then purged by selection. However, it has been argued that if genes underlying incompatibilities are themselves subject to divergent selection, then they might overcome gene flow to diverge between populations, resulting in the origin of incompatibilities. Nonetheless, there has been little explicit mathematical exploration of such scenarios for the origin of intrinsic incompatibilities during ecological speciation with gene flow. Here we explore theoretical models for the origin of intrinsic isolation where genes subject to divergent natural selection also affect intrinsic isolation, either directly or via linkage disequilibrium with other loci. Such genes indeed overcome gene flow, diverge between populations, and thus result in the evolution of intrinsic isolation. We also examine barriers to neutral gene flow. Surprisingly, we find that intrinsic isolation sometimes weakens this barrier, by impeding differentiation via ecologically based divergent selection.


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