scholarly journals It is lonely at the front: contrasting evolutionary trajectories in male and female invaders

2016 ◽  
Vol 3 (12) ◽  
pp. 160687 ◽  
Author(s):  
Cameron M. Hudson ◽  
Gregory P. Brown ◽  
Richard Shine

Invasive species often exhibit rapid evolutionary changes, and can provide powerful insights into the selective forces shaping phenotypic traits that influence dispersal rates and/or sexual interactions. Invasions also may modify sexual dimorphism. We measured relative lengths of forelimbs and hindlimbs of more than 3000 field-caught adult cane toads ( Rhinella marina ) from 67 sites in Hawai'i and Australia (1–80 years post-colonization), along with 489 captive-bred individuals from multiple Australian sites raised in a ‘common garden’ (to examine heritability and reduce environmental influences on morphology). As cane toads spread from east to west across Australia, the ancestral condition (long limbs, especially in males) was modified. Limb length relative to body size was first reduced (perhaps owing to natural selection on locomotor ability), but then increased again (perhaps owing to spatial sorting) in the invasion vanguard. In contrast, the sex disparity in relative limb length has progressively decreased during the toads' Australian invasion. Offspring reared in a common environment exhibited similar geographical divergences in morphology as did wild-caught animals, suggesting a genetic basis to the changes. Limb dimensions showed significant heritability (2–17%), consistent with the possibility of an evolved response. Cane toad populations thus have undergone a major shift in sexual dimorphism in relative limb lengths during their brief (81 years) spread through tropical Australia.

2018 ◽  
Vol 151 (3) ◽  
pp. 293-302 ◽  
Author(s):  
Michael R. Sekor ◽  
Steven J. Franks

Background and aims – Introduced populations can potentially experience strong selection and rapid evolution. While some retrospective studies have shown rapid evolution in introduced populations in the past, few have directly tested for and characterized evolution as it occurs. Here we use an experimental introduction to directly observe and quantify evolution of multiple traits in a plant population introduced to a novel environment. Methods – We experimentally introduced seeds of the annual plant Brassica rapa L. (Brassicaceae) from a location in southern California into multiple replicated plots in New York. We allowed the populations to naturally evolve for 3 years. Following the resurrection approach, we compared ancestors and descendants planted in common garden conditions in New York in multiple phenotypic traits. Key results – Within only three generations, there was significant evolution of several morphological, phenological, and fitness traits, as well as substantial variation among traits. Despite selection for larger size during the three years following introduction, there was evolution of smaller size, earlier flowering time, and shorter duration of flowering. Although there were rapid evolutionary changes in traits, descendants did not have greater fitness than ancestors in New York, indicating a lack of evidence for adaptive evolution, at least over the timeframe of the study. Conclusions – This study found rapid evolution of several morphological and phenological traits, including smaller plant size and shorter time to flowering, following introduction, confirming that evolution can rapidly occur during the early stages of colonization. Many traits evolved in the opposite direction predicted from phenotypic selection analysis, which suggests that the resurrection approach can reveal unanticipated evolutionary changes and can be very useful for studying contemporary evolution.


2020 ◽  
Author(s):  
Robert Rauschkolb ◽  
Lisa Henres ◽  
Caroline Lou ◽  
Sandrine Godefroid ◽  
Lara Dixon ◽  
...  

Plant populations must continuously adapt to the impacts of ongoing global climate change, including warmer temperatures and more extreme weather events. We can detect such evolutionary changes within plant populations through the resurrection approach whereby plants grown from seeds stored in seed banks (“ancestors”) are compared to freshly collected seeds from the same populations (“descendants”) in common garden experiments. In this study we used the resurrection approach in two multi-species experiments to investigate changes in phenotypic traits and drought tolerance of European plant species from two biogeographic regions. In the seedling survival experiment using seedlings of four Mediterranean species, watering was ceased and day of mortality recorded. We found that descendants survived significantly longer without any watering but these seedlings were smaller than the ancestral seedlings. In the watering response experiment we investigated phenotypic responses to drought in adult plants of nine species originating from temperate climatic regions in Europe. We found that descendant plants were significantly taller under well-watered conditions but smaller under drought than their ancestors, thus showing stronger plasticity. Our study suggests that plants have already evolved phenotypically, including through changes in trait means and plasticity, within the last decades. The observed evolutionary changes are consistent with adaptation to increased drought. More generally, the resurrection approach proved to be a useful tool to study rapid evolutionary processes in plants under climate change. Future studies should include fitness measures and comparative transplantations of descendants and ancestors into their original habitat to disentangle adaptive from non-adaptive responses to recent climate change.


Author(s):  
Natasha Kruger ◽  
John Measey ◽  
Giovanni Vimercati ◽  
Anthony Herrel ◽  
Jean Secondi

Abstract In amphibians, spatial sorting progressively enhances the dispersal capacities of dispersing stages in expanding populations but may enhance or limit the performance of the earlier non-dispersing stages. Phenotypic traits of non-dispersing tadpoles and metamorphs can be coupled, through carry-over effects and trade-offs, or decoupled to dispersal traits in adults. We used the globally invasive amphibian, Xenopus laevis, to examine whether spatial sorting of adult phenotypes affects the phenotype of larval stages to metamorphosis in the core and at the periphery of an invasive population in France. We combined common garden laboratory and outdoor experiments to test the effect of parental pond location (core or periphery) on morphology, development and survival to metamorphosis and found no differences between tadpoles. After metamorphosis, the only difference observed in either of the experiments was the larger body size of metamorphs from the periphery, and then only when reared in the laboratory. Differences in metamorph size may indicate that a shift of dispersal traits occur after metamorphosis in X. laevis. Thus, our findings illustrate that decoupled evolution through spatial sorting can lead to changes of X. laevis adult phenotypes that would enhance dispersal without affecting the phenotype of tadpoles before metamorphosis.


2021 ◽  
Author(s):  
Anna Kirschbaum ◽  
Oliver Bossdorf ◽  
J F Scheepens

Abstract Aims Plant populations in managed grasslands are subject to strong selection exerted by grazing, mowing and fertilization. Many previous studies showed that this can cause evolutionary changes in mean trait values, but little is known about the evolution of phenotypic plasticity in response to land use. In this study, we aimed to elucidate the relationships between phenotypic plasticity – specifically, regrowth ability after biomass removal – and the intensity of grassland management and levels of temporal variation therein. Methods We conducted an outdoor common garden experiment to test if plants from more intensively mown and grazed sites showed an increased ability to regrow after biomass removal. We used three common plant species from temperate European grasslands, with seed material from 58 – 68 populations along gradients of land-use intensity, ranging from extensive (only light grazing) to very intensive management (up to four cuts per year). Important findings In two out of three species, we found significant population differentiation in regrowth ability after clipping. While variation in regrowth ability was unrelated to the mean land-use intensity of populations of origin, we found a relationship with its temporal variation in P. lanceolata, where plants experiencing less variable environmental conditions over the last 11 years showed stronger regrowth in reproductive biomass after clipping. Therefore, while mean grazing and mowing intensity may not select for regrowth ability, the temporal stability of the environmental heterogeneity created by land use may have caused its evolution in some species.


2019 ◽  
Vol 66 (4) ◽  
pp. 417-424
Author(s):  
Gregorio Moreno-Rueda ◽  
Abelardo Requena-Blanco ◽  
Francisco J Zamora-Camacho ◽  
Mar Comas ◽  
Guillem Pascual

Abstract Predation is one of the main selective forces in nature, frequently selecting potential prey for developing escape strategies. Escape ability is typically influenced by several morphological parameters, such as morphology of the locomotor appendices, muscular capacity, body mass, or fluctuating asymmetry, and may differ between sexes and age classes. In this study, we tested the relationship among these variables and jumping performance in 712 Iberian green frogs Pelophylax perezi from an urban population. The results suggest that the main determinant of jumping capacity was body size (explaining 48% of variance). Larger frogs jumped farther, but jumping performance reached an asymptote for the largest frogs. Once controlled by structural body size, the heaviest frogs jumped shorter distances, suggesting a trade-off between fat storage and jumping performance. Relative hind limb length also determined a small but significant percentage of variance (2.4%) in jumping performance—that is, the longer the hind limbs, the greater the jumping capacity. Juveniles had relatively shorter and less muscular hind limbs than adults (for a given body size), and their jumping performance was poorer. In our study population, the hind limbs of the frogs were very symmetrical, and we found no effect of fluctuating asymmetry on jumping performance. Therefore, our study provides evidence that jumping performance in frogs is not only affected by body size, but also by body mass and hind limb length, and differ between age classes.


2011 ◽  
Vol 366 (1563) ◽  
pp. 344-356 ◽  
Author(s):  
Monique Borgerhoff Mulder ◽  
Bret A. Beheim

Studying fitness consequences of variable behavioural, physiological and cognitive traits in contemporary populations constitutes the specific contribution of human behavioural ecology to the study of human diversity. Yet, despite 30 years of evolutionary anthropological interest in the determinants of fitness, there exist few principled investigations of the diverse sources of wealth that might reveal selective forces during recent human history. To develop a more holistic understanding of how selection shapes human phenotypic traits, be these transmitted by genetic or cultural means, we expand the conventional focus on associations between socioeconomic status and fitness to three distinct types of wealth—embodied, material and relational. Using a model selection approach to the study of women's success in raising offspring in an African horticultural population (the Tanzanian Pimbwe), we find that the top performing models consistently include relational and material wealth, with embodied wealth as a less reliable predictor. Specifically, child mortality risk is increased with few household assets, parent nonresidency, child legitimacy, and one or more parents having been accused of witchcraft. The use of multiple models to test various hypotheses greatly facilitates systematic comparative analyses of human behavioural diversity in wealth accrual and investment across different kinds of societies.


2018 ◽  
Vol 9 ◽  
Author(s):  
Yunshi Li ◽  
Xiukun Wu ◽  
Tuo Chen ◽  
Wanfu Wang ◽  
Guangxiu Liu ◽  
...  

2021 ◽  
Author(s):  
Neil Robert Caton ◽  
David M. G. Lewis

Numerous taxa have evolved physiological appendage-based weaponry to increase damage output in violent fights, but no research has empirically shown that Homo sapiens upper appendages have uniquely evolved to increase resource-provisioning potential in real-world combat. In Study 1, we used actual fight outcome data (N = 715 fighters) to examine multiple competing hypotheses—the striker, defender, grappler, and knockout hypotheses—for the evolution of Homo sapiens upper limb length, controlling for approximately a dozen confounding variables (e.g., biacromial width, lower limb length, age, weight, height). There was exclusive support for the knockout hypothesis: upper limb length increases fighting success through knockout power. There was also evidence for a real-world association between biacromial width and knockout power. Because sexual dimorphism often emerges from selection on morphological structures that improve male’s fighting success, we consequently expected sexual dimorphism in upper limb length. Studies 2a-2d provided powerful evidence for this new universal sexual dimorphism in upper limb length. Even after controlling for weight, height, and lower limb length, males exhibited longer upper limbs than females across the globe: from mixed-martial-artists (Study 2a) and Croatian adolescents (but not pre-pubertal children; Study 2b) to older Singaporean adults (Study 2c) and over 6,000 United States Army personnel (Study 2d) born across seven major world regions (Africa, Europe, Asia, Oceania, and North, Central, and South America). Combined, our results provide comprehensive support for the argument that intrasexual selection has uniquely shaped Homo sapiens upper limb length to enhance fighting performance in real-world combat.


2021 ◽  
Vol 2 (2) ◽  
pp. 041-049
Author(s):  
Djalal Ardjoun Khalil ◽  
Mahamat Ibrahim Souleymane ◽  
Issa Youssouf ◽  
Madjina Tellah ◽  
Mopate Logtene Youssouf ◽  
...  

This work was carried out on the phenotypic characteristics of the Kababich sheep exploited in the peri-urban zone of N'Djamena (Chad). This phenotypic characterization of Kababich sheep should be continued on local breeds for genetic improvement and objective optimization of productivity. The objective of this study is the characterization of phenotypically Kababich sheep exploited in the peri-urban area of ​​N'Djamena-Chad. It was conducted in 39 farms and involved 1035 sheep aged less than one year old. Phenotypic traits were measured according to the guideline defined by FAO. A total of 12 variables were measured including five qualitative and seven quantitative. The results obtained show a positively significant correlation (p> 0.001) between the age of the sheep estimated by the breeder and the dentition (0.83). The ears are drooping and measure 17.90 ± 2.77 cm. The color of the brown dress (fawn) and the smooth and short coat are dominant. The females are matte and the rams of brown dress have horns in the forms of the vestiges. The Kababich is large with a height at the withers of 81.50 ± 9.40 cm, a rump height of 83.24 ± 9.42 cm and a chest circumference of 88.29 ± 9.22 cm. The body is 72.82 ± 9.63 cm long, has a basin width of 19.89 ± 2.53 cm and a chest depth of 40.68 ± 5.16 cm. These measurements show that Kababich is a meat breed by excellence. In addition, the sexual dimorphism very accentuated in this race orients towards a valorization of the young males in the fattening workshops.


2021 ◽  
pp. 329-340
Author(s):  
Anna Kuparinen

Contemporary evolution that occurs across ecologically relevant time scales, such as a few generations or decades, can not only change phenotypes but also feed back to demographic parameters and the dynamics of populations. This chapter presents a method to make phenotypic traits evolve in mechanistic individual-based simulations. The method is broadly applicable, as demonstrated through its applications to boreal forest adaptation to global warming, eco-evolutionary dynamics driven by fishing-induced selection in Atlantic cod, and the evolution of age at maturity in Atlantic salmon. The main message of this chapter is that there may be little reason to exclude phenotypic evolution in analyses of population dynamics, as these can be modified by evolutionary changes in life histories. Future challenges will be to integrate rapidly accumulating genomic knowledge and an ecosystem perspective to improve population projections and to better understand the drivers of population dynamics.


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