Indicator Of Relatedness Research Articles

Multiple social encounters can eliminate Crozier’s paradox and stabilise genetic kin recognition

Crozier’s paradox suggests that genetic kin recognition will not be evolutionarily stable. The problem is that more common tags (markers) are more likely to be recognised and helped. This causes common tags to increase in frequency, and hence eliminates the genetic variability that is required for genetic kin recognition. It has therefore been assumed that genetic kin recognition can only be stable if there is some other factor maintaining tag diversity, such as the advantage of rare alleles in host-parasite interactions. We show that allowing for multiple social encounters before each social interaction can eliminate Crozier’s paradox, because it allows individuals with rare tags to find others with the same tag. We also show that rare tags are better indicators of relatedness, and hence better at helping individuals avoid interactions with non-cooperative cheats. Consequently, genetic kin recognition provides an advantage to rare tags that maintains tag diversity, and stabilises itself.

Relatedness between numerically small Dutch Red dairy cattle populations and possibilities for multibreed genomic prediction

Red dairy breeds are a valuable cultural and historical asset, and often a source of unique genetic diversity. However, they have difficulties competing with other, more productive, dairy breeds. Improving competitiveness of Red dairy breeds, by accelerating their genetic improvement using genomic selection, may be a promising strategy to secure their long-term future. For many Red dairy breeds, establishing a sufficiently large breed-specific reference population for genomic prediction is often not possible, but may be overcome by adding individuals from another breed. Relatedness between breeds strongly decides the benefit of adding another breed to the reference population. To prioritize among available breeds, the effective number of chromosome segments (Me) can be used as an indicator of relatedness between individuals from different breeds. The Me is also an important parameter in determining the accuracy of genomic prediction. The Me can be estimated both within a population and between 2 populations or breeds, as the reciprocal of the variance of genomic relationships. We investigated relatedness between 6 Dutch Red cattle breeds, Groningen White Headed (GWH), Dutch Friesian (DF), Meuse-Rhine-Yssel (MRY), Dutch Belted (DB), Deep Red (DR), and Improved Red (IR), focusing primarily on the Me, to predict which of those breeds may benefit from including reference animals of the other breeds. All of these breeds, except MRY, are under high risk of extinction. Our results indicated high variability of Me, especially between Me ranging from ∼3,500 to ∼17,400, indicating different levels of relatedness between the breeds. Two clusters are especially important, one formed by MRY, DR, and IR, and the other comprising DF and DB. Although relatedness between breeds within each of these 2 clusters is high, across-breed genomic prediction is still limited by the current number of genotyped individuals, which for many breeds is low. However, adding MRY individuals would increase the reference population of DR substantially. We estimated that between 11 and 133 individuals from other breeds are needed to achieve accuracy of genomic prediction equivalent to using one additional individual from the same breed. Given the variation in size of the breeds in this study, the benefit of a multibreed reference population is expected to be lower for larger breeds than for the smaller ones.

Factors affecting accuracy of estimated effective number of chromosome segments for numerically small breeds.

For numerically small breeds, obtaining a sufficiently large breed‐specific reference population for genomic prediction is challenging or simply not possible, but may be overcome by adding individuals from another breed. To prioritize among available breeds, the effective number of chromosome segments (M e) can be used as an indicator of relatedness between individuals from different breeds. The M e is also an important parameter in determining the accuracy of genomic prediction. The M e can be estimated both within a population and between two populations or breeds, as the reciprocal of the variance of genomic relationships. However, the threshold for number of individuals needed to accurately estimate within or between populations M e is currently unknown. It is also unknown if a discrepancy in number of genotyped individuals in two breeds affects the estimates of M e between populations. In this study, we conducted a simulation that mimics current domestic cattle populations in order to investigate how estimated M e is affected by number of genotyped individuals, single‐nucleotide polymorphism (SNP) density and pedigree availability. Our results show that a small sample of 10 genotyped individuals may result in substantial over or underestimation of M e. While estimates of within population M e were hardly affected by SNP density, between population M e values were highly dependent on the number of available SNPs, with higher SNP densities being able to detect more independent chromosome segments. When subtracting pedigree from genomic relationships before computing M e, estimates of within population M e were three to four times higher than estimates with genotypes only; however, between M e estimates remained the same. For accurate estimation of within and between population M e, at least 50 individuals should be genotyped per population. Estimates of within M e were highly affected by whether pedigree was used or not. For within M e, even the smallest SNP density (~11k) resulted in accurate representation of family relationships in the population; however, for between M e, many more markers are needed to capture all independent segments.

Indicators of Relatedness in Adolescent Male Groups: Toward a Qualitative Description

Self-determination theorists (SDT) argue that the satisfaction of the need for relatedness is essential for growth and well-being. However, the current research has yet to account for the unique ways in which adolescent males engage in behaviors to fulfill their need for relatedness within their peer groups. This qualitative study investigates relatedness in six 16-to 17-year-old adolescent males. Independent observations of videotape data and a collaborative analysis revealed 13 main indicators of moment-to-moment relatedness. These indicators include expressing belonging, referring to shared experiences, and helping others out. The indicators of relatedness are discussed in the context of SDT, and additional theoretical frameworks provide an integrative understanding of the construct. Implications for research on the need for relatedness across diverse settings and populations are discussed and the utility of the indicators for professionals who work with adolescent males is considered.

Genetic Relatedness and Chemical Profiles in an Unusually Peaceful Eusocial Bee

Colonies of the stingless bee Tetragonilla collina frequently occur in unusually high densities and in direct neighborhood (nest aggregations), in rainforests of Southeast Asia. To investigate whether close relatedness and/or similar chemical profiles facilitate the co-occurrence of multiple T. collina colonies, we investigated aggressive behavior, genetic relatedness and cuticular hydrocarbon (CHC) profiles within and between colonies and nest aggregations. Although 17 out of 19 colonies within aggregations were largely unrelated, intraspecific aggression between different colonies was basically absent both within and among aggregations. This lack of aggression should favor social parasitism and hence the occurrence of unrelated individuals within a colony. However, low within-colony relatedness was found in only five out of 19 colonies where it may be explained by queen turnover or the occurrence of foreign workers. CHC profiles of colonies within and among aggregations were statistically different. However, many workers could chemically not be assigned to their maternal colony, indicating considerable overlap among colonies in odor profiles of workers. Moreover, odor profiles tended to be more similar within than among aggregations, although most colonies were unrelated. Thus, CHC profiles were a poor indicator of relatedness in T. collina. The lack of correlation between relatedness and chemical similarity in T. collina may be explained by the incorporation of resin-derived terpenes in their CHC profiles. The composition of these terpenes was highly similar among colonies, particularly within aggregations, hence potentially decreasing chemical distinctiveness and increasing behavioral tolerance.

Social Evolution: The Decline and Fall of Genetic Kin Recognition

Animals should benefit from the ability to recognise their kin, yet curiously this faculty is often absent. New theory confirms that genetic kin recognition is inherently unstable, explaining its rarity.

Kinship in colonial tuco-tucos: evidence from group composition and population structure

Kinship plays a significant role in shaping the social and genetic structures of many vertebrate populations. Evidence of kinship, however, may be substantially influenced by the spatial and temporal scales over which co-ancestry is monitored. For example, while data on social group composition may yield little indication of relatedness among reproductive partners, data on the demographic structure of a population may reveal considerable shared ancestry among mates. We explored relationships among social group composition, individual movements, and population-level patterns of kinship using data from a 7-year field study of the colonial tuco-tuco (Ctenomys sociabilis), a group-living subterranean rodent that is endemic to southwestern Argentina. Our analyses indicate that social groups are composed of 1–4 generations of closely related females and a single, immigrant male, suggesting that reproductive partners are not related to one another. Monitoring individual movements, however, revealed that (1) most male dispersal occurs within the local population and (2) most new social groups are founded by females born in the study population, indicating that individuals reared in different burrow systems may share considerable co-ancestry. Simulation analyses revealed that up to 67% of reproductive partnerships consist of animals that share co-ancestry within the last 5–7 generations. Thus, while analyses of social group composition provide little evidence of kinship among reproductive partners, population-level analyses of dispersal and group formation suggest that co-ancestry among mates is common. These findings have important implications for interpreting social interactions and genetic structure in this species.

ALTRUISM VIA KIN-SELECTION STRATEGIES THAT RELY ON ARBITRARY TAGS WITH WHICH THEY COEVOLVE

Hamilton's rule explains when natural selection will favor altruism between conspecifics, given their degree of relatedness. In practice, indicators of relatedness (such as scent) coevolve with strategies based on these indicators, a fact not included in previous theories of kin recognition. Using a combination of simulation modeling and mathematical extension of Hamilton's rule, we demonstrate how altruism can emerge and be sustained in a coevolutionary setting where relatedness depends on an individual's social environment and varies from one locus to another. The results support a very general expectation of widespread, and not necessarily weak, conditional altruism in nature.

Progress and pitfalls in systematics: cladistics, DNA and morphology*

SUMMARY The ‘natural system’ of organisms reflects their phylogenetic relationship. It is the result of an historical process and has to be inferred from the available evidence. In the morphological phenotype, historical traces are intermeshed with functional adaptations. Overall similarity, even if quantified, can be a misleading indicator of relatedness. Cladistics uses shared derived character states (synapomorphies) to identify groups of common ancestry. Synapomorphies are mostly inferred from their taxonomic context. If apparently equally valid characters suggest mutually exclusive groups, parsimony is invoked: a phylogenetic reconstruction requiring a minimum of evolutionary steps to describe the present character distribution is accepted as the most likely one. Cladistics sets very stringent requirements for informative characters, and a rigorous analysis of morphology is likely to yield very few reliable characters. The direct analysis of DNA sequences provides theoretically the optimal evidence for phylogenetic reconstruction. In practice, very little of this information is readily accessible. Occasionally major sequence rearrangements can be unequivocal synapomorphies. Many phylogenetic problems can be solved by comparative sequencing of an appropriate segment of DNA. Comparative sequencing of the chloroplast gene rbcL has become the model for such studies. Molecular data have confirmed much traditional taxonomy, elucidated doubtful cases and corrected misinterpretations. Molecular data also have clearly shown the limits of the cladistic approach by revealing both known and previously unsuspected modes of reticulate evolution. Molecular approaches separate phylogenetic reconstruction from biological evaluation and will never replace morphological analysis in Systematics. However, molecular methods also facilitate the direct investigation of morphological evolution by revealing the genetic basis of morphogenesis in model systems or by permitting the genetic analysis of diagnostic character changes by genetic mapping.

Minnows First, Then Trout

Abstract In the past two decades there has been a dramatic change in the practice of classifying organisms based on a rigorous, new methodology called cladistics, which defines relationships based on the distribution of shared derived characters. This approach, coupled with new information, has led to changes in our concepts of the relationships of major fish groups. These changes should be reflected in newer classifications and lists. For many purposes it is desirable to list related taxa together so that it is easy to make comparisons among them. The order in which taxa are listed is important as an indication of relatedness. Some variations in arrangement are equivalent and interchangeable; others imply relationships that are contrary to available evidence and must be rejected.

Purification and properties of a 90-kDa nuclear actin-binding protein.

A 90 kDa actin-binding nuclear protein (ABNP) with a pI of 5.2 has been purified from the 0.7 M NaCl extracted residue fraction of chromatin prepared from Novikoff hepatoma cell nuclei. This residue fraction was previously shown to contain nuclear actin. Although twice the size, similar in pI, and similar in amino acid composition to actin, the tryptic peptide map for ABNP is distinct and contains the appropriate number of tyrosine-containing tryptic peptides for a protein of 90,000 molecular weight. A comparison of the amino acid composition of ABNP with those reported in the literature for gelsolin and villin, using a calculation of S delta Q as an indication of relatedness, results in values of 30 and 27, respectively. Actin-binding activity, however, was demonstrated for both crude and gel purified ABNP using a gel-overlay technique that employs 125I-G-actin to detect specific actin-binding proteins.