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opencc-zeroDec 2013View details →

Data from: Hybridization, natural selection and evolution of reproductive isolation: a 25-years survey of an artificial sympatric area between two mosquito sibling species of the Aedes mariae complex

Natural selection can act against maladaptive hybridization between co-occurring divergent populations leading to evolution of reproductive isolation among them. A critical unanswered question about this process that provides a basis for the theory of speciation by reinforcement, is whether natural selection can cause hybridization rates to evolve to zero. Here we investigated this issue in two sibling mosquitoes species, Aedes mariae and Ae. zammitii, that show post-mating reproductive isolation (F1 males sterile) and partial pre-mating isolation (different height of mating swarms) that could be reinforced by natural selection against hybridization. In 1986, we created an artificial sympatric area between the two species and sampled about 20,000 individuals over the following 25 years. Between 1986 to 2011, the composition of mating swarms and the hybridization rate between the two species were investigated across time in the sympatric area. Our results showed that Ae. mariae and Ae. zammitii have not completed reproductive isolation since their first contact in the artificial sympatric area. We have discussed the relative role of factors such as time of contact, gene flow, strength of natural selection, and biological mechanisms causing prezygotic isolation to explain the observed results.

opencc-zeroDec 2009View details →

Data from: Strict monandry in the ponerine army ant genus Simopelta suggests that colony size and complexity drive mating system evolution in social insects

Altruism in social insects has evolved between closely related full-siblings. It is therefore of considerable interest why some groups have secondarily evolved low within-colony relatedness, which in turn affects the relatedness incentives of within-colony cooperation and conflict. The highest queen mating frequencies, and therefore among the lowest degrees of colony relatedness, occur in Apis honeybees and army ants of the subfamilies Aenictinae, Ecitoninae, and Dorylinae, suggesting that common life-history features such as reproduction by colony fission and male biased numerical sex-ratios have convergently shaped these mating systems. Here we show that ponerine army ants of the genus Simopelta, which are distantly related but similar in general biology to other army ants, have strictly monandrous queens. Preliminary data suggest that workers reproduce in queenright colonies, which is in sharp contrast to other army ants. We hypothesize that differences in mature colony size and social complexity may explain these striking discrepancies.

Data from: Workforce effects and the evolution of complex sociality in wild Damaraland mole rats

Explaining the evolution of eusocial and cooperatively breeding societies demands that we understand the effects of workforce size on the reproductive success of breeders. This challenge has yet to be addressed in the family that arguably exhibits the most extreme outcomes of vertebrate social evolution, the African mole rats (Bathyergidae), leaving the ultimate causes of their many unusual adaptations open to debate. Here we report—using a 14-year field study of wild Damaraland mole rats, Fukomys damarensis—that workers appear to have strong but unusual effects on offspring. Groups with larger workforces exhibited substantially higher rates of offspring recruitment while maintaining high juvenile survival rates, relationships that may have favored the evolution of the delayed dispersal, cooperation, morphological specialization, and unusual patterns of longevity that characterize such societies. Offspring reared by larger workforces also showed slower growth, however. That reduced offspring growth in larger groups has also been documented under ad lib. food conditions in the laboratory raises the possibility that this reflects socially induced growth restraint rather than simple constraints on resource availability. Our findings shed new light on the evolution of complex sociality in this enigmatic clade and highlight further departures from the norms reported for other cooperative vertebrates.

opencc-zeroDec 2019View details →

Data from: Is evolution predictable? quantitative genetics under complex genotype-phenotype maps

<p>A fundamental aim of post-genomic 21st century biology is to understand the genotype-phenotype map (GPM) or how specific genetic variation relates to specific phenotypic variation. Quantitative genetics approximates such maps using linear models, and has developed methods to predict the response to selection in a population. The other major field of research concerned with the GPM, developmental evolutionary biology or evo-devo, has found the GPM to be highly nonlinear and complex. Here we quantify how the predictions of quantitative genetics are affected by the complex, nonlinear maps found in developmental biology. We found that the disagreements between predicted and observed responses to selection are common, roughly in a third of generations, systematic and due to nonlinear nature of the genotype-phenotype map. They occur at all time scales, even from one generation to the next. Our results are a step towards integrating the fields studying the GPM.</p>

Data from: Evolution and biogeography of the endemic Roucela complex (Campanulaceae: Campanula) in the eastern Mediterranean

At the intersection of geological activity, climatic fluctuations, and human pressure, the Mediterranean Basin – a hotspot of biodiversity – provides an ideal setting for studying endemism, evolution, and biogeography. Here, we focus on the Roucela complex (Campanula subgenus Roucela), a group of 13 bellflower species found primarily in the eastern Mediterranean Basin. Plastid and low-copy nuclear markers were employed to reconstruct evolutionary relationships and estimate divergence times within the Roucela complex using both concatenation and species tree analyses. Niche modeling, ancestral range estimation, and diversification analyses were conducted to provide further insights into patterns of endemism and diversification through time. Diversification of the Roucela clade appears to have been primarily the result of vicariance driven by the breakup of an ancient landmass. We found geologic events such as the formation of the mid-Aegean trench and the Messinian Salinity Crisis to be historically important in the evolutionary history of this group. Contrary to numerous past studies, the onset of the Mediterranean climate has not promoted diversification in the Roucela complex and, in fact, may be negatively affecting these species. This study highlights the diversity and complexity of historical processes driving plant evolution in the Mediterranean Basin.

Data from: Evolution and conservation on top of the world: Phylogeography of the Marbled Water Frog (Telmatobius marmoratus species complex; Anura, Telmatobiidae) in protected areas of Chile

The Andean Altiplano has served as a complex setting throughout its history, driving dynamic processes of diversification in several taxa. We investigated phylogeographic processes in the Telmatobius marmoratus species complex occurring in this region by studying the geographic patterns of genetic variability, genealogies, and historical migration, using the cytochrome b (cyt-b) gene as a marker. DNA sequences from Telmatobius gigas and Telmatobius culeus, Bolivian species with an uncertain taxonomic status, were also included. Additionally, we evaluated the phylogenetic diversity (PD) represented within Chilean protected areas and the complementary contribution from unprotected populations. Phylogenetic reconstructions from 148 cyt-b sequences revealed 4 main clades, one of which corresponded to T. culeus. T. gigas was part of T. marmoratus clade indicating paraphyletic relationships. Haplotypes from Chilean and Bolivian sites were not reciprocally monophyletic. Geographic distribution of lineages, spatial Bayesian analysis, and migration patterns indicated that T. marmoratus displays a weaker geographic structure than expected based on habitat distribution and physiological requirements. Demographic and statistical phylogeography analyses pointed out to a scenario of recent population expansion and high connectivity events of a more recent age than the post Last Glacial Maximum, probably associated to more humid events in Altiplano. PD of T. marmoratus populations within protected areas represents 55.6% of the total estimated PD. The unprotected populations that would contribute the most to PD are Caquena and Quebe (21%). Recent evolutionary processes and paleoclimatic changes, potentially driving shifts in habitat connectivity levels and population sizes, could explain the phylogeographic patterns recovered herein.

opencc-zeroDec 2012View details →

Data from: Major histocompatibility complex class I evolution in songbirds: universal primers, rapid evolution and base compositional shifts in exon 3

Genes of the Major Histocompatibility Complex (MHC) have become an important marker for the investigation of adaptive genetic variation in vertebrates because of their critical role in pathogen resistance. However, despite significant advances in the last few years the characterization of MHC variation in non-model species still remains a challenging task due to the redundancy and high variation of this gene complex. Here we report the utility of a single pair of primers for the cross-amplification of the third exon of MHC class I genes, which encodes the more polymorphic half of the peptide-binding region (PBR), in oscine passerines (songbirds; Aves: Passeriformes), a group especially challenging for MHC characterization due to the presence of large and complex MHC multigene families. In our survey, although the primers failed to amplify exon 3 from two suboscine passerine birds, they amplified exon 3 of multiple MHC class I genes in all 16 species of oscine songbirds tested, yielding a total of 120 sequences. The 16 songbird species belong to 14 different families, primarily within the Passerida, but also in the Corvida. Using a conservative approach based on the analysis of cloned amplicons (n = 16) from each species, we found between 3 and 10 MHC sequences per individual. Each allele repertoire was highly divergent, with the overall number of polymorphic sites per species ranging from 33 to 108 (out of 264 sites) and the average number of nucleotide differences between alleles ranging from 14.67 to 43.67. Our survey in songbirds allowed us to compare macroevolutionary dynamics of exon 3 between songbirds and non-passerine birds. We found compelling evidence of positive selection acting specifically upon peptide-binding codons across birds, and we estimate the strength of diversifying selection in songbirds to be about twice that in non-passerines. Analysis using comparative methods suggest weaker evidence for a higher GC content in the 3rd codon position of exon 3 in non-passerine birds, a pattern that contrasts with among-clade GC patterns found in other avian studies and may suggests different mutational mechanisms. Our primers represent a useful toolfor the characterization of functional and evolutionarily relevant MHC variation across the hyperdiverse songbirds.

opencc-zeroDec 2013View details →

Data from: The trophic vacuum and the evolution of complex life cycles in trophically-transmitted helminths

Parasitic worms (helminths) frequently have complex life cycles in which they are transmitted trophically between two or more successive hosts. Sexual reproduction often takes place in high trophic-level (TL) vertebrates, where parasites can grow to large sizes with high fecundity. Direct infection of high TL hosts, while advantageous, may be unachievable for parasites constrained to transmit trophically, because helminth propagules are unlikely to be ingested by large predators. Lack of niche overlap between propagule and definitive host (the trophic transmission vacuum) may explain the origin and/or maintenance of intermediate hosts, which overcome this transmission barrier. We show that nematodes infecting high TL definitive hosts tend to have more successive hosts in their life cycles. This relationship was modest, though, driven mainly by the minimum TL of hosts, suggesting that the shortest trophic chains leading to a host define the boundaries of the transmission vacuum. We also show that alternative modes of transmission, like host penetration, allow nematodes to reach high TLs without intermediate hosts. We suggest that widespread omnivory as well as parasite adaptations to increase transmission probably reduce, but do not eliminate, the barriers to the transmission of helminths through the food web.

Data from: The evolution of life cycle complexity in aphids: ecological optimization, or historical constraint?

For decades, biologists have debated why many parasites have obligate multi-host life cycles. Here, we use comparative phylogenetic analyses of aphids to evaluate the roles of ecological optimization and historical constraint in the evolution of life cycle complexity. If life cycle complexity is adaptive, it should be evolutionarily labile, i.e., change in response to selection. We provide evidence that this is true in some aphids (aphidines), but not others (non-aphidines) – groups that differ in the intensity of their relationships with primary hosts. Next, we test specific mechanisms by which life cycle complexity could be adaptive or a constraint. We find that among aphidines there is a strong association between complex life cycles and polyphagy but only a weak correlation between life cycle complexity and reproductive mode. In contrast, among non-aphidines the relationship between life cycle complexity and host breadth is weak but the association between complex life cycles and sexual reproduction is strong. Thus, although the adaptiveness of life cycle complexity appears to be lineage specific, across aphids, life cycle evolution appears to be tightly linked with the evolution of other important natural history traits.

FIGURE 5 in On the evolution of the species complex Pachycondyla chinensis (Hymenoptera: Formicidae: Ponerinae), including the origin of its invasive form and description of a new species

FIGURE 5. Characters of male coloration and mandible of P. nakasujii (A, B), P. chinensis (C, D) and P. luteipes (E, F). Black arrows indicate the mandible.

FIGURE 6 in On the evolution of the species complex Pachycondyla chinensis (Hymenoptera: Formicidae: Ponerinae), including the origin of its invasive form and description of a new species

FIGURE 6. Currently known distribution of P. nakasujii (A) and P. chinensis (B) in Japan. Each dot may indicate more than one site if they are located less than 20 km apart.

FIGURE 2 in On the evolution of the species complex Pachycondyla chinensis (Hymenoptera: Formicidae: Ponerinae), including the origin of its invasive form and description of a new species

FIGURE 2. Mean (± SD) of the biometric measurements of P. nakasujii and P. chinensis (n = 13 and 35, respectively).

FIGURE 4 in On the evolution of the species complex Pachycondyla chinensis (Hymenoptera: Formicidae: Ponerinae), including the origin of its invasive form and description of a new species

FIGURE 4. Characters of worker propodeum and petiole. The left side of worker propodeum and petiole of P. nakasujii (A), P. chinensis (C) and P. luteipes (E), and the posterior face of worker petiole of P. nakasujii (B), P. chinensis (D) and P. luteipes (F) (Scanning electron microscopy photographs). Horizontal white arrow: PW. Also see Japanese Ant Database Group (2003).

FIGURE 1 in On the evolution of the species complex Pachycondyla chinensis (Hymenoptera: Formicidae: Ponerinae), including the origin of its invasive form and description of a new species

FIGURE 1. Bayesian phylogenetic tree of the species complex Pachycondyla chinensis based on mitochondrial sequences of the COI region. The corresponding posterior probabilities (≥0.70) are shown by the branch. The horizontal bar represents a distance of 0.1 substitutions per site. GenBank accession numbers are shown in parentheses.

FIGURE 6 in A new species of bright-eyed treefrog (Mantellidae) from Madagascar, with comments on call evolution and patterns of syntopy in the Boophis ankaratra complex

FIGURE 6. Comparative oscillograms (top) and corresponding spectrograms (bottom) of single notes of the advertisement calls on the same time scale in the Boophis ankaratra complex. Species shown are: (A) B. boppa (Maharira); (B) B. miadana (Andohahela); (C) B. ankaratra (Maharira); (D) B. schuboeae (Ambatolahy); and (E) B. haingana (Andohahela). Spectrogram was produced in SEEWAVE using a Hanning window length of 512.

FIGURE 12 in A new species of bright-eyed treefrog (Mantellidae) from Madagascar, with comments on call evolution and patterns of syntopy in the Boophis ankaratra complex

FIGURE 12. Reproductive behavior of species of the B. ankaratra complex. (A) A typical perch of a male B. boppa preparing to call; (B) a male B. boppa during emission of advertisement call; and (C) amplexus, male not collected, female KU 336829 of B. boppa.

FIGURE 9 in A new species of bright-eyed treefrog (Mantellidae) from Madagascar, with comments on call evolution and patterns of syntopy in the Boophis ankaratra complex

FIGURE 9. Minimum-spanning haplotype network for the nuclear exon DNAH-3 in the B. albipunctatus group. Ticks on branches represent single nucleotide changes. Branch lengths are not meaningful.

FIGURE 1 in A new species of bright-eyed treefrog (Mantellidae) from Madagascar, with comments on call evolution and patterns of syntopy in the Boophis ankaratra complex

FIGURE 1. The distribution of species in the Boophis albipunctatus group in southeastern Madagascar. The black dotted line shows the boundaries of Ranomafana National Park (RNP), and partially colored circles indicate syntopy of their corresponding species. The numbered localities are as follows (species occurring at each locality abbreviated as BA, B. ankaratra; BB, B. boppa, BL, B. luciae; BS, B. schuboeae): Within RNP: (1) Maharira (BA, BB; type locality of BB); (2) Valohoaka (BL); (3) Vohiparara (BS); (4) Andranoroa river (BA, BB); (5) Sakaroa (BB); (6) Ambatolahy (BL, BS); (7–8) Imaloka (BB, BL); and (9) Andemaka (BB, BL). Outside RNP: (10) Ambohitsara-Ranomafana (BL); (11) Farihimazava (BA, BB); (12) Soamazaka (BA, BB); and (13) Vohisokina (BA, BB). Note that at Ambohitsara, records also exist for another species of the group (B. albipunctatus) that is not discussed herein.

FIGURE 5 in A new species of bright-eyed treefrog (Mantellidae) from Madagascar, with comments on call evolution and patterns of syntopy in the Boophis ankaratra complex

FIGURE 5. Comparative photographs of members of the Boophis ankaratra complex. (A) Boophis ankaratra; (B) Boophis haingana; (C) Boophis miadana; and (D) Boophis schuboeae.

FIGURE 8 in A new species of bright-eyed treefrog (Mantellidae) from Madagascar, with comments on call evolution and patterns of syntopy in the Boophis ankaratra complex

FIGURE 8. Results of phylogenetic analysis of the concatenated 16S alignment for maximum likelihood (ML) and Bayesian (BA) analyses. Topology is a consensus tree from MrBayes. Significant support for ML and BA analyses are indicated by the black circles at the nodes (analyses were completely consistent). Note that Boophis boppa is strongly supported as reciprocally monophyletic with respect to all other species of the B. ankaratra complex.