scholarly journals The coevolution of mammae number and litter size

2020 ◽  
Author(s):  
Thomas A. Stewart ◽  
Ihna Yoo ◽  
Nathan S. Upham
Keyword(s):  
Life History ◽  
Litter Size ◽  
Geographic Distribution ◽  
Species Level ◽  
Life History Strategies ◽  
Gestation Length ◽  
Offspring Survival ◽  
The One ◽  
Analyze Data

AbstractMammals are unique in provisioning their offspring with milk, lactiferous nourishment produced in glandular organs called mammae. Mammae number is hypothesized to coevolve with litter size, acting as a constraint on offspring survival. However, predicted canonical relations between mammae number and litter size (i.e., the ‘one-half’ and ‘identity’ rules) are untested across Mammalia. Here we analyze data for 2,301 species and show how these characters coevolve. In Mammalia, mammae number approximates the maximum reported litter size of a species, and mammae number explains more variation in litter size than other species-level traits (mass, gestation length, diet, and seasonality of contemporary geographic distribution). Clades show differences in these patterns, indicating that certain life history strategies might break the ‘rules’ of mammary evolution. Mammae number is an underappreciated constraint on fecundity that has influenced the radiation of mammals.

Are life-history strategies of Norway rats (Rattus norvegicus) and house mice (Mus musculus) dependent on environmental characteristics?

2014 ◽  
Vol 41 (2) ◽  
pp. 172 ◽  
Author(s):  
M. V. Vadell ◽  
I. E. Gómez Villafañe ◽  
R. Cavia
Keyword(s):  
Life History ◽  
Litter Size ◽  
House Mouse ◽  
Urban Environments ◽  
Demographic Characteristics ◽  
Life History Strategies ◽  
Environmental Characteristics ◽  
Norway Rat ◽  
Rural Environments ◽  
Freezing Temperatures

Context Life-history theory attempts to explain the way in which an organism is adapted to its environment as well as explaining the differences in life-history strategies among and within species. Aims The aim of this paper was to compare life-history traits of the Norway rat and the house mouse living in different habitats and geographic regions so as to find patterns related to environmental characteristics on the basis of published ecological studies conducted before 2011. Methods The environments where rodent populations lived were characterised according to climate type, occurrence of freezing temperatures and frost, degree of anthropisation and trapping location. Four demographic characteristics were analysed. A canonical correspondence analysis was performed to explain the effects of environmental variables on the demographic characteristics of rodents. Information was gathered from 35 articles published between 1945 and 2010. Key results Most populations of both species showed differences in abundance throughout the year, but no defined pattern was common among populations. The pregnancy rate of Norway rat was highest during spring and autumn in urban environments, during spring and winter in rural environments and during summer in sylvan habitats. House mouse populations were most frequently reported to experience high pregnancy rates during summer. Contrary to urban and rural populations, in sylvan environments the occurrence of a reproductive break was the most commonly reported pattern for both species. Litter size of Norway rat depended on the degree of anthropisation and the occurrence of freezing temperatures and frost. Litter size was greater in rural environments and in areas without freezing temperatures and frost. House mouse did not show differences in litter size resulting from any of the environmental characteristics analysed. Conclusions Both species are able to modify their reproductive strategies according to environmental characteristics, especially according to the degree of anthropisation of the environment. In sylvan areas, where animals are more exposed to seasonal changes in weather conditions, changes in reproductive investment are more evident. Implications Regarding the implications for rodent control, the best time to apply control measures could be winter in sylvan and urban environments. In rural environments, the best time for conducting control efforts is less clear, although cold seasons seem also to be the best.

scholarly journals The impact of maternal genetic merit and country of origin on ewe reproductive performance, lambing performance and ewe survival

2021 ◽  
Author(s):  
N Fetherstone ◽  
N McHugh ◽  
T M Boland ◽  
F M McGovern
Keyword(s):  
New Zealand ◽  
Birth Weight ◽  
Litter Size ◽  
Country Of Origin ◽  
Reproductive Traits ◽  
Gestation Length ◽  
Genetic Merit ◽  
Genetic Groups ◽  
One Year ◽  
The Impact

Abstract The objective of this study was to investigate the impact of the ewe’s maternal genetic merit and country of origin (New Zealand or Ireland) on ewe reproductive, lambing and productivity traits. The study was performed over a four year period (2016 to 2019) and consisted of three genetic groups: high maternal genetic merit New Zealand (NZ), high maternal genetic merit Irish (High Irish) and low maternal genetic merit Irish (Low Irish) ewes. Each group contained 30 Suffolk and 30 Texel ewes, selected based on the respective national maternal genetic indexes; i.e. either the New Zealand Maternal Worth (New Zealand group) or the €uro-star Replacement index (Irish groups). The impact of maternal genetic merit on reproductive traits such as litter size; lambing traits such as gestation length, birth weight, lambing difficulty, mothering ability, and productivity traits such as the number of lambs born and weaned were analyzed using linear mixed models. For binary traits, the impact of maternal genetic merit on reproductive traits such as conception to first AI service; lambing traits such as dystocia, perinatal lamb mortality and productivity traits such as ewe survival were analyzed using logistic regression. New Zealand ewes outperformed Low Irish ewes for conception to first AI (P<0.05) and litter size (P=0.05). Irish ewes were more likely to suffer from dystocia (6.84 (High Irish) and 8.25 (Low Irish) times) compared to NZ ewes (P<0.001); birth weight and perinatal mortality did not differ between groups (P>0.05). Lambs born from NZ ewes were 4.67 (95% CI: 1.89 to 11.55; P<0.001) and 6.54 (95% CI: 2.56 to 16.71; P<0.001) times more likely to stand up and suckle unassisted relative to lambs born from High or Low Irish ewes, respectively. New Zealand and High Irish ewes had a greater number of lambs born and weaned throughout the duration of the study compared to their Low Irish counterparts (P<0.001). New Zealand ewes tended to be more likely to survive from one year to the next compared to Low Irish ewes (P=0.07). Irish ewes of high maternal genetic merit outperformed their Low counterparts in total number of lambs born and weaned per ewe, but performance did not differ across other traits investigated. This highlights the importance of continuous development of the Irish maternal sheep index to ensure favourable improvements in reproductive, lambing and productivity traits at farm level. Overall, results demonstrate the suitability of NZ genetics in an Irish production system.

scholarly journals Natural variation in plant telomere length is associated with flowering time

2021 ◽  
Author(s):  
Jae Young Choi ◽  
Liliia R Abdulkina ◽  
Jun Yin ◽  
Inna B Chastukhina ◽  
John T Lovell ◽  
...  
Keyword(s):  
Life History ◽  
Telomere Length ◽  
Flowering Time ◽  
Dna Sequences ◽  
Genome Wide Association Study ◽  
Genomic Analysis ◽  
Life History Strategies ◽  
Length Variation ◽  
Chromosomal Structure ◽  
Chromosome Integrity

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.

Intraspecific hybridization, life history strategies and potential invasion success in a parasitoid wasp

2012 ◽  
Vol 26 (6) ◽  
pp. 1311-1329 ◽  
Author(s):  
Chiara Benvenuto ◽  
Sandrine Cheyppe-Buchmann ◽  
Gérald Bermond ◽  
Nicolas Ris ◽  
Xavier Fauvergue
Keyword(s):  
Life History ◽  
Parasitoid Wasp ◽  
Invasion Success ◽  
Life History Strategies ◽  
Intraspecific Hybridization

scholarly journals High Genetic Variance in Life-History Strategies within Invasive Populations by Way of Multiple Introductions

2008 ◽  
Vol 18 (5) ◽  
pp. 363-367 ◽  
Author(s):  
Benoît Facon ◽  
Jean-Pierre Pointier ◽  
Philippe Jarne ◽  
Violette Sarda ◽  
Patrice David
Keyword(s):  
Life History ◽  
Genetic Variance ◽  
Life History Strategies ◽  
Multiple Introductions

Demography of Xenosaurus platyceps (Squamata: Xenosauridae): a comparison between tropical and temperate populations

2008 ◽  
Vol 29 (2) ◽  
pp. 245-256 ◽  
Author(s):  
Carissa Jones ◽  
Isaac Rojas-González ◽  
Julio Lemos-Espinal ◽  
Jaime Zúñiga-Vega
Keyword(s):  
Life History ◽  
Population Growth ◽  
Adult Mortality ◽  
Life History Strategies ◽  
Relative Importance ◽  
Theoretical Frameworks ◽  
Population Growth Rates ◽  
Relative Contribution ◽  
Two Populations ◽  
Average Fitness

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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