LIFE HISTORY STRATEGIES IN EXTREME ENVIRONMENTS: COMPARATIVE DEMOGRAPHY OF ARCTIC AND ALPINE PTARMIGAN

Ecology ◽  
2005 ◽  
Vol 86 (8) ◽  
pp. 2176-2186 ◽  
Author(s):  
Brett K. Sandercock ◽  
Kathy Martin ◽  
Susan J. Hannon
2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Randal A. Singer ◽  
Jon A. Moore ◽  
Edward L. Stanley

Abstract The deep ocean is frequently assumed to be a homogeneous system lacking the same diverse life history strategies found in shallower waters. However, as our methods for exploring the deep ocean improve, common assumptions about dispersal, reproduction and behavior are constantly being challenged. Fishes exhibit the most diverse reproductive strategies among vertebrates. Understanding life history strategies in deep-sea environments is lacking for many species of fishes. Here, we report a novel reproductive strategy where a fish (Parazen pacificus) provides parental care via mouth brooding. This behavior is observed from a specimen collected with eggs present in the buccal cavity, along with other specimens exhibiting pre-brooding morphologies. This is the first description of this unique life history trait in a deep-sea fish and fills in a gap in the larval literature for this family of fishes and prompts further investigation into other novel reproductive modes of deep-sea fauna.


2006 ◽  
Vol 84 (12) ◽  
pp. 1789-1795 ◽  
Author(s):  
Xin Lu ◽  
Bin Li ◽  
Juan Juan Liang

Rana chensinensis (David, 1875) is a temperate anuran endemic to northern China. We examined differences in demographic traits of the populations from three elevations (1400, 1700, and 2000 m) along a montane river in 2002. We found that frogs from higher elevations had delayed maturity, a larger size at maturity, and slower growth rates compared with frogs at lower elevations. This life-history model is similar to observations of other amphibians living in montane areas. However, discordance with the expected model occurred between neighboring populations and the variation was sex-specific. Mid-elevation adult males were significantly older and larger than their low-elevation congeners, but they were statistically similar in age and size to frogs from high elevations; females from mid elevations were not statistically different in age and size from females from our low-elevation site, but they were significantly younger and smaller than high-elevation females. These variations may be related to sexual differences in life-history strategies, which might not covary systematically when elevational gradients are set at a finer scale. At each elevation, the sex ratio was skewed towards females; females also matured later, lived longer, and were larger. Age was a major factor related to size, but other factors played a role in shaping size differences both between populations and between sexes.


2021 ◽  
Author(s):  
Jae Young Choi ◽  
Liliia R Abdulkina ◽  
Jun Yin ◽  
Inna B Chastukhina ◽  
John T Lovell ◽  
...  

Abstract Telomeres are highly repetitive DNA sequences found at the ends of chromosomes that protect the chromosomes from deterioration during cell division. Here, using whole genome re-sequencing and terminal restriction fragment assays, we found substantial natural intraspecific variation in telomere length in Arabidopsis thaliana, rice (Oryza sativa), and maize (Zea mays). Genome-wide association study (GWAS) mapping in A. thaliana identified 13 regions with GWAS-significant associations underlying telomere length variation, including a region that harbors the telomerase reverse transcriptase (TERT) gene. Population genomic analysis provided evidence for a selective sweep at the TERT region associated with longer telomeres. We found that telomere length is negatively correlated with flowering time variation not only in A. thaliana, but also in maize and rice, indicating a link between life history traits and chromosome integrity. Our results point to several possible reasons for this correlation, including the possibility that longer telomeres may be more adaptive in plants that have faster developmental rates (and therefore flower earlier). Our work suggests that chromosomal structure itself might be an adaptive trait associated with plant life history strategies.


2012 ◽  
Vol 26 (6) ◽  
pp. 1311-1329 ◽  
Author(s):  
Chiara Benvenuto ◽  
Sandrine Cheyppe-Buchmann ◽  
Gérald Bermond ◽  
Nicolas Ris ◽  
Xavier Fauvergue

2008 ◽  
Vol 18 (5) ◽  
pp. 363-367 ◽  
Author(s):  
Benoît Facon ◽  
Jean-Pierre Pointier ◽  
Philippe Jarne ◽  
Violette Sarda ◽  
Patrice David

2008 ◽  
Vol 29 (2) ◽  
pp. 245-256 ◽  
Author(s):  
Carissa Jones ◽  
Isaac Rojas-González ◽  
Julio Lemos-Espinal ◽  
Jaime Zúñiga-Vega

Abstract There appears to be variation in life-history strategies even between populations of the same species. For ectothermic organisms such as lizards, it has been predicted that demographic and life-history traits should differ consistently between temperate and tropical populations. This study compares the demographic strategies of a temperate and a tropical population of the lizard Xenosaurus platyceps. Population growth rates in both types of environments indicated populations in numerical equilibrium. Of the two populations, we found that the temperate population experiences lower adult mortality. The relative importance (estimated as the relative contribution to population growth rate) of permanence and of the adult/reproductive size classes is higher in the temperate population. In contrast, the relative importance for average fitness of fecundity and growth is higher in the tropical population. These results are consistent with the theoretical frameworks about life-historical differences among tropical and temperate lizard populations.


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