An overview of the phylogeny and diversity of eukaryotes

Our understanding of eukaryote biology is dominated by the study of land plants, animals and fungi. However, these are only three isolated fragments of the full diversity of extant eukaryotes. The majority of eu-karyotes, in terms of major taxa and probably also sheer numbers of cells, consists of exclusively or predomi-nantly unicellular lineages. A surprising number of these lineages are poorly characterized. Nonetheless, they are fundamental to our understanding of eukaryote biology and the underlying forces that shaped it. This article consists of an overview of the current state of our understanding of the eukaryote tree. This includes the identity of the major groups of eukaryotes, some of their important, defining or simply interesting features and the pro-posed relationships of these groups to each other.

Multivariate analyses of skull morphology inform the taxonomy and evolution of geomyoid rodents

Morphological analyses are critical to quantify phenotypic variation,identify taxa,inform phylogenetic relationships,and shed light on evolutionary patterns.This work is particularly important in groups that display great morphological disparity.Such is the case in geomyoid rodents,a group that includes 2 of the most species-rich families of rodents in North America:the Geomyidae(pocket gophers)and the Heteromyidae(kangaroo rats,pocket mice,and their relatives).We assessed variation in skull morphology(including both shape and size)among geomyoids to test the hypothesis that there are statistically significant differences in skull measurements at the family,genus,and species levels.Our sample includes 886 specimens representing all geomyoid genera and 39 species.We used the geometric mean to compare size across taxa.We used 14 measurements of the cranium and lower jaw normalized for size to compare shape among and within taxa.Our results show that skull measurements enable the distinction of geomyoids at the family,genus,and species levels.There is a larger amount of size variation within Geomyidae than within Heteromyidae.Our phylomorphospace analysis shows that the skull shape of the common ancestor of all geomyoids was more similar to the common ancestor of heteromyids than that of geomyids.Geomyid skulls display negative allometry whereas heteromyid skulls display positive allometry.Within heteromyids,dipodomyines,and non-dipodomyines show significantly different allometric patterns.Future analyses including fossils will be necessary to test our evolutionary hypotheses.

Selectively breeding for high voluntary physical activity in female mice does not bestow inherent characteristics that resemble eccentric remodeling of the heart,but the mini-muscle phenotype does

Physical activity engagement results in a variety of positive health outcomes,including a reduction in cardiovascular disease risk partially due to eccentric remodeling of the heart.The purpose of this investigation was to determine if four replicate lines of High Runner mice that have been selectively bred for voluntary exercise on wheels have a cardiac phenotype that resembles the outcome of eccentric remodeling.Adult females(average age 55 days)from the 4 High Runner and 4 non-selected control lines were anaesthetized via vaporized isoflurane,then echocardiographic images were collected and analyzed for structural and functional differences.High Runner mice in general had lower ejection fractions compared to control mice lines(2-tailed p=0.0236)and tended to have thicker walls of the anterior portion of the left ventricle(p=0.065).However,a subset of the High Runner individuals,termed mini-muscle mice,had greater ejection fraction(p=0.0006),fractional shortening percentage(p<0.0001),and ventricular mass at dissection(p<0.0027 with body mass as a covariate)compared to non-mini muscle mice.Mice from replicate lines bred for high voluntary exercise did not all have inherent positive cardiac functional or structural characteristics,although a genetically unique subset of mini-muscle individuals did have greater functional cardiac characteristics,which in conjunction with their previously described peripheral aerobic enhancements(e.g.,increased capillarity)would partially account for their increased VO2max.

Colorful facial markings are associated with foraging rates and affiliative relationships in a wild group-living cichlid fish

Many animals use color to signal their quality and/or behavioral motivations.Colorful signals have been well studied in the contexts of competi-tion and mate choice;however,the role of these signals in nonsexual,affiliative relationships is not as well understood.Here,we used wild social groups of the cichlid fish Neolamprologus pulcher to investigate whether the size of a brightly colored facial patch was related to 1)individual quality,2)social dominance,and/or 3)affiliative relationships.Individuals with larger patches spent more time foraging and tended to perform more aggressive acts against conspecific territory intruders.We did not find any evidence that the size of these yellow patches was related to social rank or body size,but dominant males tended to have larger patches than dominant females.Additionally,patch size had a rank-specific relationship with the number of affiliative interactions that individuals engaged in.Dominant males with large patches received fewer affiliative acts from their groupmates compared to dominant males with small patches.However,subordinates with large patches tended to receive more affiliative acts from their groupmates while performing fewer affiliative acts themselves.Taken together,our results suggest that patch size reflects interindividual variation in foraging effort in this cichlid fish and offer some of the first evidence that colorful signals may shape affiliative relationships withinwildsocialgroups.

Intragroup social dynamics vary with the presence of neighbors in a cooperatively breeding fish

Conflict is an in here nt part of social life in group-living species. Group members may mediate conflict through submissive and affiliative behaviors, which can reduce aggression, stabilize dominance hierarchies, and foster group cohesion. The frequency and resolution of within-group conflict may vary with the presenee of neighboring groups. Neighbors can threaten the territory or resources of the whole group, promoting behaviors that foster within-group cohesion. However, neighbors may also foster conflict of interests among group members: opportunities for subordinate dispersal may alter conflict among dominants and subordinates while opportunities for extrapair reproduction may increase conflict between mates. To understand how neighbors mediate within-group conflict in the cooperatively breeding fish Neolamprologus pulcher, we measured behavioral dynamics and social network structure in isolated groups, groups recently exposed to neighbors, and groups with established neighbors. Aggression and submission between the dominant male and female pair were high in isolated groups, but dominant aggression was directly primarily at subordinates when groups had neighbors. This suggests that neighbors attenuate conflict between mates and foster conflict between dominants and subordinates. Further, aggression and submission between similarly sized group members were most frequent when groups had neighbors, suggesting that neighbors induce rank-related conflict. We found relatively little change in within-group affiliative networks across treatments, suggesting that the presence of neighbors does not alter behaviors associated with promoting group cohesion. Collectively, these results provide some of the first empirical insights into the extent to which intragroup behavioral networks are mediated by intergroup interactions and the broader social context.

Population genetic structure and demographic history of the Chinese endemic Mongoloniscus sinensis(Dollfus,1901) (Isopoda:Oniscidea)

The soil animal Mongoloniscus sinensis （Dollfus, 1901） is distributed in Northern China together with three other congeneric species only found in Asia. Compared to European and North American Oniscidea, little phylogeographic information about this Asian genus has been reported. Herein, we infer the genetic structure and demographic history of M. sinensis based on mitochondrial cytochrome c oxidase subunit I （mtCoI）. The total dataset included 193 individuals from 26 locations in four provinces （Shanxi, Henan, Hebei and Shandong） of China. Most of the 87 haplotypes were unique to a sampling location, but seven haplotypes were shared among the populations. The results showed that high genetic differentiation exists both within populations and among the groups and populations ofM. sinensis. According to the distribution of phylogenic clades and geographic analyses, it is suggested that mountain ranges play an important role in population separation and that the possible evolutionary trajectory of this species is from north to south. The most likely place of origin is the Northeast Plain of China with an estimated time of isolation separating populations around 8 Mya.

Wildfire and floral herbivory alter reproduction and pollinator mutualisms of Yuccas and Yucca moths

Aims Wildfire and ungulate herbivore pressure are increasing globally due to human activities,including arid ecosystems that are sensitive to disturbance,and are highly dependent on pollinator mutualisms.We evaluated how wildfire and ungulate herbivore pressure influ-ence plant reproductive success and pollinator mutualisms.Methods We evaluated flower production,floral herbivory,pollinator visita-tion and fruit set of two Yucca species with highly specialized polli-nator mutualisms(Yucca baccata and Yucca brevifolia)in unburned and burned landscapes created by fires that occurred in the Mojave Desert in 2005.Important Findings Yucca baccata plants in burned landscapes had a greater propor-tion of flowering individuals than plants in unburned areas(23 versus 12%).All Y.brevifolia individuals in burned and unburned landscapes produced flowers.Sixty-four percent of Y.baccata inflorescences were removed due to herbivory by cattle in burned areas,compared to 51%in unburned locations.Forty-two percent of Y.brevifolia inflorescences on branches≤2 m in height were removed in burned areas due to cattle herbivory compared to 39%in unburned locations.However,we did not observe any inflores-cence removal on Y.brevifolia branches>2 m where the major-ity of Y.brevifolia inflorescences are produced.Yucca moths,the only known pollinators of these two species,visited Y.brevifolia uniformly in burned and unburned areas but failed to visit Y.bac-cata altogether.Yucca brevifolia had strong fruit production,but not a single fruit was produced among the thousands of flowering Y.baccata plants surveyed.Floral herbivory and the loss of obligate pollinator mutualisms appear to be critical threats to the long-term viability of Y.baccata populations in this landscape.the reproduc-tive resilience of Y.brevifolia and the maintenance of its pollinator populations appear to be due to its taller stature,which allows verti-cal escape of flowers from ungulate herbivores.Removal of live-stock during the flowering period appears to be a critical first step to restoring Y.baccata’s pollinator mutualisms and capacity for sexual reproduction.

Sexual dimorphism in cranial shape and size in geomyoid rodents:multivariate and evolutionary perspectives

Geomyoid rodents provide a great study system for the analysis of sexual dimorphism.They are polygynic and many inhabit harsh arid environments thought to promote sexual dimorphism.In fact,there has been extensive work published on the sexual size dimorphism of individual populations and species within this rodent clade.However,little work has been undertaken to assess the evolutionary patterns and processes associated with this sexual dimorphism.We use multivariate analyses of cranial measurements in a phylogenetic framework to determine the distribution of size and shape dimorphism among geomyoids and test for Rensch’s rule.Our results suggest that sexual dimorphism is more common in geomyids than heteromyids,but it is not in fact universal.There is evidence for variation in sexual dimorphism across populations.Additionally,in many taxa,geographic variation appears to overwhelm existing sexual dimorphism.We find support for the repeated independent evolution of shape and size dimorphism across geomyoid taxa,but we do not find support for an association between size and shape dimorphism.There is no evidence for Rensch’s rule in geomyoids,whether at the superfamily or family level.Together,our findings suggest that there is no single explanation for the evolution of sexual dimorphism in geomyoids and that,instead,it is the product of numerous evolutionary events.Future studies incorporating phylogenetic relationships will be necessary to paint a more complete picture of the evolution of sexual dimorphism in geomyoids.

Climate Optimum rejuvenates the Mediterranean marine world

The Mediterranean,a sea with an already eventful history,is again undergoing an extreme change.A combination of general warming of the Mediterranean Sea and contact with the Indopacific world through the Suez Canal has set the stage for massive changes in the biota that inhabit this sea.For over a century,tropical species of all taxa have been migrating back into the Mediterranean,suggesting a duplication or restoration of a mid-Pliocene Piacenzian or late Miocene Tortonian situation.Test cases are presented in three major taxa.It is not a serial invasion by individual rogue exotic and damaging species,as often wrongly assumed and asserted.Despite its unique biogeographic magnitude being recognized,an opportunity to study the progress of this phenomenon is being missed.This is because of the changed priorities in research,the acute taxonomic impediment and to the geopolitical difficulties in cooperation.Nonetheless,the limitations of the restoration process are defined and a careful future outlook is presented.

Finding your scientific story by writing backwards

To succeed,a scientist must write well.Substantial guidance exists on writing papers that follow the classic Introduction,Methods,Results,and Discussion(IMRaD)structure.Here,we fill a critical gap in this pedagogical canon.We offer guidance on developing a good scientific story.This valuable—yet often poorly achieved—skill can increase the impact of a study and its likelihood of acceptance.A scientific story goes beyond presenting information.It is a cohesive narrative that engages the reader by presenting and solving a problem,with a beginning,middle,and end.To create this narrative structure,we urge writers to consider starting at the end of their study,starting with writing their main conclusions,which provide the basis of the Discussion,and then work backwards:Results→Methods→refine the Discussion→Introduction→Abstract→Title.In this brief and informal editorial,we offer guidance to a wide audience,ranging from upper-level undergraduates(who have just conducted their first research project)to senior scientists(who may benefit from re-thinking their approach to writing).To do so,we provide specific instruction,examples,and a guide to the literature on how to“write backwards”,linking scientific storytelling to the IMRaD structure.