The composition of the founding population of Iceland: A new perspective from 3D analyses of basicranial shape

House Mice in the Atlantic Region: Genetic Signals of Their Human Transport

BACKGROUND/OBJECTIVES

The colonization history of house mice reflects the maritime history of humans that passively transported them worldwide. We investigated western house mouse colonization in the Atlantic region through studies of mitochondrial D-loop DNA sequences from modern specimens.

METHODS

We assembled a dataset of 758 haplotypes derived from 2765 mice from 47 countries/oceanic archipelagos (a combination of new and published data). Our maximum likelihood phylogeny recovered five previously identified clades, and we used the haplotype affinities within the phylogeny to infer house mouse colonization history, employing statistical tests and indices. From human history, we predefined four European source areas for mice in the Atlantic region (Northern Europe excluding Scandinavia, Southern Europe, Scandinavia, and Macaronesia) and we investigated the colonization from these source areas to different geographic areas in the Atlantic region.

RESULTS

Our inferences suggest mouse colonization of Scandinavia itself from Northern Europe, and Macaronesia from both Southern Europe and Scandinavia/Germany (the latter likely representing the transport of mice by Vikings). Mice on North Atlantic islands apparently derive primarily from Scandinavia, while for South Atlantic islands, North America, and Sub-Saharan Africa, the clearest source is Northern Europe, although mice on South Atlantic islands also had genetic inputs from Macaronesia and Southern Europe (for Tristan da Cunha). Macaronesia was a stopover for Atlantic voyages, creating an opportunity for mouse infestation. Mice in Latin America also apparently had multiple colonization sources, with a strong Southern European signal but also input from Northern Europe and/or Macaronesia.

CONCLUSIONS

D-loop sequences help discern the broad-scale colonization history of house mice and new perspectives on human history.

Investigating temporal bone variation of colonial populations from St-Lawrence Valley, Quebec: A 3D geometric morphometric approach

OBJECTIVES

In Quebec, genetic and genealogical research are used to document migratory events and family structures since colonial times, because bioarchaeological analysis is limited by poor skeletal preservation. This article aims to fill this gap by exploring past population structure in the St-Lawrence Valley from the French (1683-1760) and British (1760-1867) regimes using morphological variation of well-preserved temporal bones.

MATERIALS AND METHODS

3D geometric morphometrics shape data from seven populations (five Catholics of French descent and two Protestants of British descent; n = 214) were collected from temporal bones. Using Procrustes distances and both MANOVA and Discriminant Function Analysis, morphological differences were measured to calculate affinities patterns among populations. Shape variations were explored with between-group analysis, Mahalanobis distances and quantified by means of Fst estimates using Relethford-Blangero analysis.

RESULTS

Despite strong affinities between all Catholic cemeteries, all show divergent morphological regional diversity -especially Montreal and the fortified villages dedicated to its defense. Montreal exhibits low increase in morphological variance over three centuries. As our results show no morphological differences between the Catholic and the Protestant cemeteries in Montreal, this fact may highlight the potential presence of Irish or admixed individuals in Montreal cemeteries after the British takeover.

DISCUSSION

Patterns of morphological diversity highlighted that French colonists did not equally contribute to the descendant populations as reflected by significant interregional variation. Although historical records show that French and English-speaking populations did not tend to admix, morphological affinities between Protestants and Catholics in the beginning of the industrial era in Montreal could reflect the genetic contribution of Catholic Irish migrants.

RESEARCH HIGHLIGHTS

All Catholic cemeteries display distinct morphologies, highlighting differential contributions from French colonists and founder effects, which have increased regional differences. Montreal Catholic (French descent) and Protestant (English colonists) cemeteries show significant morphological affinities at the beginning of the industrial era. The Irish migration following the British conquest may explain morphological similarities observed between Catholic and Protestant cemeteries.

Fitness and Power: The Contribution of Genetics to the History of Differential Reproduction

Textual evidence from pre-modern societies supports the prediction that status differences among men translate to variance in reproductive success. In recent years, analysis of genetic data has opened up new ways of studying this relationship. By investigating cases that range over several millennia, these analyses repeatedly document the replacement of local men by newcomers and reveal instances of exceptional reproductive success of specific male lineages. These findings suggest that violent population transfers and conquests could generate considerable reproductive advantages for male dominants. At the same time, this does not always seem to have been the case. Moreover, it is difficult to link such outcomes to particular historical characters or events, or to identify status-biased reproductive inequalities within dominant groups. The proximate factors that mediated implied imbalances in reproductive success often remain unclear. A better understanding of the complex interplay between social power and genetic fitness will only arise from sustained transdisciplinary engagement.