Hamish G. Spencer

Does space always matter in the origin of biological species (2007)

Winter, David J, Spencer, Hamish G

For the last 40 years one of the most contentious issues in evolutionary biology has been determining the role that spatial separation of populations plays in the generation of new species. Most...

The effect of spatial population structure on levels of genetic variation (2007)

Star, Bastiaan, Spencer, Hamish G

A vast amount of genetic variation is a striking hallmark of natural populations, and is vital to the adaptation and long-term survival of a species. Just why this variation is there, however, is...

Predictive adaptive responses and human evolution (2005)

Gluckman, Peter D., Hanson, Mark A., Spencer, Hamish G.

The importance of a single genotype being able to produce different phenotypes in different environments (phenotypic plasticity) is widely recognized in evolutionary theory and its adaptive...

CLADOGENESIS AS THE RESULT OF LONG-DISTANCE RAFTING EVENTS IN SOUTH PACIFIC TOPSHELLS (GASTROPODA, TROCHIDAE) (2005)

Kirsten M. Donald, Martyn Kennedy, Hamish G. Spencer

We used DNA sequences of lecithotrophic monodontine topshells, belonging to the genera Diloma, Melagraphia, and Austrocochlea, to ascertain how this group became established over a large area of the...

Environmental influences during development and their later consequences for health and disease: implications for the interpretation of empirical studies (2005)

Gluckman, Peter D., Hanson, Mark A., Spencer, Hamish G., Bateson, Patrick

Early experience has a particularly great effect on most organisms. Normal development may be disrupted by early environmental influences; individuals that survive have to cope with the damaging...

Untangling Long Branches: Identifying Conflicting Phylogenetic Signals Using Spectral Analysis, Neighbor-Net, and Consensus Networks (2005)

Kennedy, Martyn, Holland, Barbara R., Gray, Russell D., Spencer, Hamish G.

Long-branch attraction is a well-known source of systematic error that can mislead phylogenetic methods; it is frequently invoked post hoc, upon recovering a different tree from the one expected...

Phylogeography of carnivorous snails from Northland (2004)

Spencer, Hamish G, Kennedy, Martyn

Landsnails of the subfamily Paryphantinae are active carnivores on earthworms and other snails. Most species are endemic to Northland, New Zealand, are several are of conservation concern, being...

Developmental plasticity and human health (2004)

Bateson, Patrick, Barker, David, Clutton-Brock, Timothy, Deb, Debal, D'Udine, Bruno, Foley, Robert A., ...

Many plants and animals are capable of developing in a variety of ways, forming characteristics that are well adapted to the environments in which they are likely to live. In adverse circumstances,...

The correlation between relatives on the supposition of genomic imprinting.

Spencer, Hamish G

Standard genetic analyses assume that reciprocal heterozygotes are, on average, phenotypically identical. If a locus is subject to genomic imprinting, however, this assumption does not hold. We...

Evolutionary genetic models of the ovarian time bomb hypothesis for the evolution of genomic imprinting.

Weisstein, Anton E, Feldman, Marcus W, Spencer, Hamish G

At a small number of loci in eutherian mammals, only one of the two copies of a gene is expressed; the other is silenced. Such loci are said to be "imprinted," with some having the maternally...

Further properties of Gavrilets' one-locus two-allele model of maternal selection.

Spencer, Hamish G

I derive several properties of the model proposed by Gavrilets for maternal selection at a single diallelic locus. Most notably, (i) stable oscillations of genotype frequencies (i.e., cycling) can...

The evolution of genomic imprinting via variance minimization: an evolutionary genetic model.

Weisstein, Anton E, Spencer, Hamish G

A small number of mammalian loci exhibit genomic imprinting, in which only one copy of a gene is expressed while the other is silenced. At some such loci, the maternally inherited allele is...

The effect of genetic conflict on genomic imprinting and modification of expression at a sex-linked locus.

Spencer, Hamish G, Feldman, Marcus W, Clark, Andrew G, Weisstein, Anton E

We examine how genomic imprinting may have evolved at an X-linked locus, using six diallelic models of selection in which one allele is imprintable and the other is not. Selection pressures are...

Frequency-dependent selection with dominance: a window onto the behavior of the mean fitness.

Asmussen, Marjorie A, Cartwright, Reed A, Spencer, Hamish G

Selection in which fitnesses vary with the changing genetic composition of the population may facilitate the maintenance of genetic diversity in a wide range of organisms. Here, a detailed...

Influence of Mom and Dad: Quantitative Genetic Models for Maternal Effects and Genomic Imprinting

Santure, Anna W., Spencer, Hamish G.

The expression of an imprinted gene is dependent on the sex of the parent it was inherited from, and as a result reciprocal heterozygotes may display different phenotypes. In contrast, maternal...

Population Models of Genomic Imprinting. II. Maternal and Fertility Selection

Spencer, Hamish G., Dorn, Timothy, LoFaro, Thomas

Under several hypotheses for the evolutionary origin of imprinting, genes with maternal and reproductive effects are more likely to be imprinted. We thus investigate the effect of genomic imprinting...

The correlation between relatives on the supposition of genomic imprinting.

Spencer, Hamish G

Standard genetic analyses assume that reciprocal heterozygotes are, on average, phenotypically identical. If a locus is subject to genomic imprinting, however, this assumption does not hold. We...

Evolutionary genetic models of the ovarian time bomb hypothesis for the evolution of genomic imprinting.

Weisstein, Anton E, Feldman, Marcus W, Spencer, Hamish G

At a small number of loci in eutherian mammals, only one of the two copies of a gene is expressed; the other is silenced. Such loci are said to be "imprinted," with some having the maternally...

Further properties of Gavrilets' one-locus two-allele model of maternal selection.

Spencer, Hamish G

I derive several properties of the model proposed by Gavrilets for maternal selection at a single diallelic locus. Most notably, (i) stable oscillations of genotype frequencies (i.e., cycling) can...

The evolution of genomic imprinting via variance minimization: an evolutionary genetic model.

Weisstein, Anton E, Spencer, Hamish G

A small number of mammalian loci exhibit genomic imprinting, in which only one copy of a gene is expressed while the other is silenced. At some such loci, the maternally inherited allele is...

The effect of genetic conflict on genomic imprinting and modification of expression at a sex-linked locus.

Spencer, Hamish G, Feldman, Marcus W, Clark, Andrew G, Weisstein, Anton E

We examine how genomic imprinting may have evolved at an X-linked locus, using six diallelic models of selection in which one allele is imprintable and the other is not. Selection pressures are...

Frequency-dependent selection with dominance: a window onto the behavior of the mean fitness.

Asmussen, Marjorie A, Cartwright, Reed A, Spencer, Hamish G

Selection in which fitnesses vary with the changing genetic composition of the population may facilitate the maintenance of genetic diversity in a wide range of organisms. Here, a detailed...

Influence of Mom and Dad: Quantitative Genetic Models for Maternal Effects and Genomic Imprinting

Santure, Anna W., Spencer, Hamish G.

The expression of an imprinted gene is dependent on the sex of the parent it was inherited from, and as a result reciprocal heterozygotes may display different phenotypes. In contrast, maternal...

Population Models of Genomic Imprinting. II. Maternal and Fertility Selection

Spencer, Hamish G., Dorn, Timothy, LoFaro, Thomas

Under several hypotheses for the evolutionary origin of imprinting, genes with maternal and reproductive effects are more likely to be imprinted. We thus investigate the effect of genomic imprinting...

A Chip off the Old Block: A Model for the Evolution of Genomic Imprinting via Selection for Parental Similarity

Spencer, Hamish G., Clark, Andrew G.

A consequence of genomic imprinting is that offspring are more similar to one parent than to the other, depending on which parent's genes are inactivated in those offspring. We hypothesize that...

Environmental influences during development and their later consequences for health and disease: implications for the interpretation of empirical studies

Gluckman, Peter D, Hanson, Mark A, Spencer, Hamish G, Bateson, Patrick

Early experience has a particularly great effect on most organisms. Normal development may be disrupted by early environmental influences; individuals that survive have to cope with the damaging...

Frequency-Dependent Selection and the Maintenance of Genetic Variation: Exploring the Parameter Space of the Multiallelic Pairwise Interaction Model

Trotter, Meredith V., Spencer, Hamish G.

When individuals' fitnesses depend on the genetic composition of the population in which they are found, selection is then frequency dependent. Frequency-dependent selection (FDS) is often invoked as...

Single-Locus Polymorphism in a Heterogeneous Two-Deme Model

Star, Bastiaan, Stoffels, Rick J., Spencer, Hamish G.

Environmental heterogeneity has long been considered a likely explanation for the high levels of genetic variation found in most natural populations: selection in a spatially heterogeneous...

Evolution of Fitnesses and Allele Frequencies in a Population With Spatially Heterogeneous Selection Pressures

Star, Bastiaan, Stoffels, Rick J., Spencer, Hamish G.

The level of gene flow considerably influences the outcome of evolutionary processes in structured populations with spatial heterogeneity in selection pressures; low levels of gene flow may allow...

An Asymmetric Model of Heterozygote Advantage at Major Histocompatibility Complex Genes: Degenerate Pathogen Recognition and Intersection Advantage

Stoffels, Rick J., Spencer, Hamish G.

We characterize the function of MHC molecules by the sets of pathogens that they recognize, which we call their “recognition sets.” Two features of the MHC–pathogen interaction may be important...

Evolution of Fitnesses in Structured Populations With Correlated Environments

Star, Bastiaan, Trotter, Meredith V., Spencer, Hamish G.

The outcome of selection in structured populations with spatially varying selection pressures depends on the interaction of two factors: the level of gene flow and the amount of heterogeneity among...

“It's Ok, We're Not Cousins by Blood”: The Cousin Marriage Controversy in Historical Perspective

Paul, Diane B, Spencer, Hamish G

Marriage between first cousins is highly stigmatized in the West and, indeed, is illegal in 31 US states. But is the hostility to such marriage scientifically well-grounded?

The Generation and Maintenance of Genetic Variation by Frequency-Dependent Selection: Constructing Polymorphisms Under the Pairwise Interaction Model

Trotter, Meredith V., Spencer, Hamish G.

Frequency-dependent selection remains the most commonly invoked heuristic explanation for the maintenance of genetic variation. For polymorphism to exist, new alleles must be both generated and...

Kelp genes reveal effects of subantarctic sea ice during the Last Glacial Maximum

Fraser, Ceridwen I., Nikula, Raisa, Spencer, Hamish G., Waters, Jonathan M.

The end of the Last Glacial Maximum (LGM) dramatically reshaped temperate ecosystems, with many species moving poleward as temperatures rose and ice receded. Whereas reinvading terrestrial taxa...