Temperature-dependent genetics of thermotolerance between yeast species

Many traits of industrial and basic biological interest arose long ago, and manifest now as fixed differences between a focal species and its reproductively isolated relatives. In these systems, extant individuals can hold clues to the mechanisms by which phenotypes evolved in their ancestors. We harnessed yeast thermotolerance as a test case for such molecular-genetic inferences. In viability experiments, we showed that extant Saccharomyces cerevisiae survived at temperatures where cultures of its sister species S. paradoxus died out. Then, focusing on loci that contribute to this difference, we found that the genetic mechanisms of high-temperature growth changed with temperature. We also uncovered a robust signature of positive selection at thermotolerance loci in S. cerevisiae population sequences. We interpret these results in light of a model of gradual acquisition of thermotolerance in the S. cerevisiae lineage along a temperature cline. We propose that in an ancestral S. cerevisiae population, alleles conferring defects at a given temperature would have been resolved by adaptive mutations, expanding the range and setting the stage for further temperature advances. Together, our results and interpretation underscore the power of genetic approaches to explore how an ancient trait came to be.

The evolution of partner specificity in mutualisms

Mutualistic species vary in their level of partner specificity, which has important evolutionary, ecological, and management implications. Yet, the evolutionary mechanisms which underpin partner specificity are not fully understood. Most work on specialization focuses on the trade-off between generalism and specialism, where specialists receive more benefits from preferred partners at the expense of benefits from non-preferred partners, while generalists receive similar benefits from all partners. Because all mutualisms involve some degree of both cooperation and conflict between partners, we highlight that specialization to a mutualistic partner can be cooperative, increasing benefit to a focal species and a partner, or antagonistic, increasing resource extraction by a focal species from a partner. We devise an evolutionary game theoretic model to assess the evolutionary dynamics of cooperative specialization, antagonistic specialization, and generalism. Our model shows that cooperative specialization leads to bistability: stable equilibria with a specialist host and its preferred partner excluding all others. We also show that under cooperative specialization with spatial effects, generalists can thrive at the boundaries between differing specialist patches. Under antagonistic specialization, generalism is evolutionarily stable. We provide predictions for how a cooperation-antagonism continuum may determine the patterns of partner specificity that develop within mutualistic relationships.

How urban forest can support Protected Areas connectivity?

The highly modified urban matrix becomes an inhospitable environment for many species because the natural vegetation fragments are highly fragmented and often isolated in the landscape. Protected Areas (PAs) located closer or within urban areas may not achieve their goal of protecting local or regional biodiversity. Thus, the proposition of ecological corridors aims to connect the PAs, providing the dispersion of species in anthropogenic landscapes. In this context, this study aimed to evaluate the PAs connectivity in an urban landscape and understand if urban forest fragments can support their connectivity, generating important information for biodiversity conservation and urban planning. For this, we used models based on Graph Theory to assess the functional connectivity among PAs. The focal species used were Atlantic Forest birds. We used the participatory technique to assess their dispersal capabilities, and this information was used to create a resistance surface map. The focal species movement in the landscape was modeled through Graph Theory. This model evaluated the functional connectivity and extracted the least-cost paths between PAs and other forest fragments that designed the urban ecological network. We identified that few PAs are connected in the urban landscape of Sorocaba city and its surroundings and 28 forest fragments that are important to support the connectivity among PAs. Among these, only four fragments are located within a PA. The other 24 forest fragments located outside PAs should be the center of attention for forest conservation and restoration actions, as they can improve the connectivity between the PAs. Our results show that PAs connectivity in urban landscapes depends on incentives for native vegetation conservation on private lands once most of the important forest fragments for the PAs connectivity are located in these areas. In addition, the restoration of riparian zones is important because they compose a great ecological corridor in the urban landscape. Strategies that increase the permeability of the matrix (e.g., increasing green spaces and gardens) and restoring target fragments are also important. Finally, land-use planning, focusing on natural ecosystem conservation and combating urban sprawl, is necessary to promote PAs connectivity in urban landscapes.

Nesting common eiders (Somateria mollissima) show little behavioral response to fixed-wing drone surveys

Drones may be valuable in polar research because they can minimize researcher activity and overcome logistic, financial, and safety obstacles associated with wildlife research in Polar Regions. Because Polar species may be particularly sensitive to disturbance and some research suggests behavioral responses to drones are species-specific, there is a need for focal species-specific disturbance assessments. We evaluated behavioral responses of nesting Common Eiders (Somateria mollissima, n =19 incubating females) to first, second, or in a few cases third exposure of fixed-wing drone surveys using nest cameras. We found no effect of drone flights (F1,23 = 0, P < 1.0) or previous exposures (F1,23 = 0.75, P = 0.397) on the probability of a daily recess event (bird leaves nests). Drone flights did not impact recess length (F1,25 = 1.34, P = 0.26); however, eiders with prior drone exposure took longer recess events (F1,25 = 5.27, P = 0.03). We did not observe any overhead vigilance behaviors common in other species while the drone was in the air, which may reflect eider’s anti-predator strategies of reducing activity at nests in response to aerial predators. Surveying nesting common eider colonies with a fixed-wing drone did not result in biologically meaningful behavioral changes, providing a potential tool for research and monitoring this Polar nesting species.

The management effectiveness of protected areas in Kenya

Merely designating new and/or expanding existing protected areas (PAs) does not guarantee the protection of critical ecosystems and species. The management of PAs must be effective to sustain meaningful conservational outcomes. We inferred the management effectiveness of PAs in Kenya based on the representation of ranges and distribution of multiple diversity dimensions of terrestrial mammals and their association with governance and designation types. We hypothesized that different governance types underlie variable management efficacies, such that stricter-managed PAs have better habitats that attract more wildlife, translating to higher species diversity compared to less strictly-managed PAs, especially for focal species groups (large carnivores, large herbivores, and endangered species). The results showed nearly all terrestrial mammals in Kenya represented in at least one PA. However, the relative proportion of represented ranges were low, and analysis of spatial conservation prioritization showed significant expansion beyond current PAs needed to achieve a one third coverage of focal species’ ranges in a best-solution reserve system. Differences in PA governance and designation types were not systematically associated with diversity variances, and while there were more unique species in state-managed PAs than in privately-managed ones, averaged diversity coefficients were comparable between categories. Diversity variances explained by PA size and status year were low in a combined species pool but increased in focal species groups. These findings suggest that success in terrestrial mammal conservation in PAs in Kenya require clearly and formally streamlined definition, performance feedback, and collaboration terms between state-managed and privately-managed PAs.

Interspecific Niche Competition Increases Morphological Diversity in Multi-Species Microbial Communities

Intraspecific competition for limited niches has been recognized as a driving force for adaptive radiation, but results for the role of interspecific competition have been mixed. Here, we report the adaptive diversification of the model bacteria Pseudomonas fluorescens in the presence of different numbers and combinations of four competing bacterial species. Increasing the diversity of competitive community increased the morphological diversity of focal species, which is caused by impeding the domination of a single morphotype. Specifically, this pattern was driven by more diverse communities being more likely to contain key species that occupy the same niche as otherwise competitively superior morphotype, and thus preventing competitive exclusion within the focal species. Our results suggest that sympatric adaptive radiation is driven by the presence or absence of niche-specific competitors.

Seasonal Climate Impacts on Vocal Activity in Two Neotropical Nonpasserines

Climatic conditions represent one of the main constraints that influence avian calling behavior. Here, we monitored the daily calling activity of the Undulated Tinamou (Crypturellus undulatus) and the Chaco Chachalaca (Ortalis canicollis) during the dry and wet seasons in the Brazilian Pantanal. We aimed to assess the effects of climate predictors on the vocal activity of these focal species and evaluate whether these effects may vary among seasons. Air temperature was positively associated with the daily calling activity of both species during the dry season. However, the vocal activity of both species was unrelated to air temperature during the wet season, when higher temperatures occur. Daily rainfall was positively related to the daily calling activity of both species during the dry season, when rainfall events are scarce and seem to act as a trigger for breeding phenology of the focal species. Nonetheless, air temperature was negatively associated with the daily calling activity of the Undulated Tinamou during the wet season, when rainfall was abundant. This study improves our understanding of the vocal behavior of tropical birds and their relationships with climate, but further research is needed to elucidate the mechanisms behind the associations found in our study.

Distilling Professional Opinion to Gauge Vulnerability of Guam Avifauna to Brown Treesnake Predation

The avifauna of Guam was devastated by the introduction of the Brown Treesnake, and the restoration of native birds would need to address the problem with eradication or suppression of BTS. With eradication of the snake unlikely in the near term, and suppression capabilities limited to specific finite areas, key information for reintroductions is how low BTS abundance will likely need to be for each bird species to be re-established based on their vulnerability to BTS predation. Here, we estimate vulnerability, which can no longer be measured directly, so biologists who are familiar with one or more of seven Guam birds were surveyed to obtain their knowledge and produce quantitative vulnerability estimates. As is typical of birds adapted to islands devoid of predators, respondents judged that our focal species exhibit few predator avoidance and tolerance traits, leaving body size as the prime determinant of vulnerability. Respondent opinion also holds that any behavior that reduces the likelihood of an encounter by BTS, e.g., roosting/nesting in palm crowns, cavity nesting, and in particular urban dwelling, substantially reduces vulnerability. Our results can help inform species-specific decisions about when it may be safe to consider the release of birds on Guam depending on the relative vulnerability of each species to predation by BTS.

Lessons from 20 years of plant genome sequencing: an unprecedented resource in need of more diverse representation

The field of plant genomics has grown rapidly in the past 20 years, leading to dramatic increases in both the quantity and quality of publicly available genomic resources. With an ever-expanding wealth of genomic data from an increasingly diverse set of taxa, unprecedented potential exists to better understand the evolution and genome biology of plants. Here, we provide a contemporary view of plant genomics, including analyses on the quality of existing plant genome assemblies, the taxonomic distribution of sequenced species, and how national participation has influenced the fields development. We show that genome quality has increased dramatically in recent years, that substantial taxonomic gaps exist, and that the field has been dominated by affluent nations in the Global North, despite a wide geographic distribution of sequenced species. We identify multiple inconsistencies between the range of focal species and the national affiliation of the researchers studying the plants, which we argue are rooted in colonialism--both past and present. Falling sequencing costs paired with widening availability of analytical tools and an increasingly connected scientific community provide key opportunities to improve existing assemblies, fill sampling gaps, and, most importantly, empower a more global plant genomics community.