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P Pamilo

Publications and source records attributed to P Pamilo.

29 records · Page 2Linked to original sources
PubMed1991

Evolution of the sterile caste.

Biased sex ratios are expected to affect the conditions of the evolution of worker behaviour in malehaploid populations. In a subsocial, malehaploid species an association to female-biased brood sex ratios favours the evolution of worker behaviour. There are various reasons to expect such an association. The critical worker efficiency threshold required for worker behaviour to evolve is lower when looked at from the viewpoint of the mother than from that of the daughter. In this mother-daughter conflict, the mother can expect some help from her other offspring to resolve the conflict in her favour. In semisocial species the sex ratio biases have a less significant role and the worker behaviour can evolve more easily in malehaploid than in diploid populations. Furthermore, limited dispersal (due to the risks attached to it) is expected to favour worker behaviour in malehaploid but inbreeding in diploid populations. In addition to the genetic mechanisms that determine the critical worker efficiency threshold, it is essential to pay attention to those ecological factors that affect the actual worker efficiency in nature. Several such factors exist but it is not easy to associate them with the common occurrence of eusocial species in the Hymenoptera.

Animals↗
PubMed1989

Pancreatic degenerative atrophy in the collie breed: a hereditary disease.

In Finland pancreatic degenerative atrophy (PDA) is most commonly diagnosed in two breeds of dogs: the German Shepherd and the rough coated Collie. The incidence of PDA in the Collie breed in Finland is close to 1%. Of the 51 cases diagnosed in the Collie breed 44 could be placed in one composite pedigree. An affected dog in that pedigree had, on average, 17 affected relatives distributed in 11 different litters. This clustering strongly suggests that PDA is a hereditary disease. The pedigree data indicate that PDA could be an autosomal recessive trait, although the estimated proportion of affected offspring within litters (0.13) was lower than the expected Mendelian frequency (0.25).

Animals↗
PubMed1988

Relationships between gene trees and species trees.

It is well known that a phylogenetic tree (gene tree) constructed from DNA sequences for a genetic locus does not necessarily agree with the tree that represents the actual evolutionary pathway of the species involved (species tree). One of the important factors that cause this difference is genetic polymorphism in the ancestral species. Under the assumption of neutral mutations, this problem can be studied by evaluating the probability (P) that a gene tree has the same topology as that of the species tree. When one gene (allele) is used from each of the species involved, the probability can be expressed as a simple function of Ti = ti/(2N), where ti is the evolutionary time measured in generations for the ith internodal branch of the species tree and N is the effective population size. When any of the Ti's is less than 1, the probability P becomes considerably less than 1.0. This probability cannot be substantially increased by increasing the number of alleles sampled from a locus. To increase the probability, one has to use DNA sequences from many different loci that have evolved independently of each other.

Alleles↗
PubMed1984

Genotypic correlation and regression in social groups: multiple alleles, multiple loci and subdivided populations.

Genotypic correlations and regressions can be estimated from multiallelic data sets either by weighting the allelic effects additively or by specifically weighting the genotypic interactions. Both methods can be extended to multiple loci, but they do not fully take into account the joint segregation patterns at the loci. These genotypic statistics have a great importance in sociobiological contexts, as they can be used for genetic descriptions of social structures. In this paper I examine the two estimation methods and show how the genotypic correlation and regression coefficients from genotypic interactions are connected to other statistics of standard population genetics; special emphasis is given to the sample-size correction when intracolony correlations from small samples were estimated. I also show how genotypic correlation and regression can be estimated in subdivided populations, both in continuous populations with isolation by distance and in populations divided into separate subpopulations. The latter analysis is an example of a more general hierarchic correlation analysis.

Alleles↗
PubMed1982

Genetic population structure in polygynous formica ants.

Genetic population structures, both mating and interaction structures, were investigated in three polygynous Formica ants by examining how genotype frequencies are distributed among the nests in their populations. The study is based on electrophoretically analysed enzyme polymorphisms. The patterns of genotypic variation among single-nest workers suggest that polygyny is functional in all the three species. The observed genotype frequencies indicate outbreeding within the study areas, and no spatial microdifferentiation in gene frequencies is detected. The coexistent gynes in nests of both F. transkaucasica and F. polyctena are genetically related to each other, and the same holds for worker nest mates. These results support the hypothesis that polygyny is favoured by kin selection. The lack of genetic relatedness among gyne nest mates in the highly polygynous F. aquilonia suggests that additional factors, such as mutualism or parental parasitism, are probably involved in the evolution of polygyny.

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