Ecological Genetics of Riparian and Maritime Species in Carex L. sect. Phacocystis Dumort.

Abstract

Carex sect. Phacocystis Dumort. is one of the largest sections of Carex L. and an evolutionary complex and diverse group, found across a large geographical range of temperate and boreal areas in North America and Europe. These species are primarily wind pollinated and capable of both asexual and sexual reproduction.

A significant proportion of the section occupy fairly narrow niches in maritime and aquatic habitats. This diversity, habitat specificity of individual species, coupled with rapid evolutionary capacity within dynamic habitats provides suitable opportunity to address topical ecological genetic questions previously unaddressed in the literature. Four areas have been investigated utilising both genetic microsatellites and morphometric approaches.

In the riparian species C. aquatilis, populations within individual river systems are genetically distinct with bidirectional gene flow, though they are not genetically isolated from other river systems. Isolated populations show isolation by distance.

Genetic structure of C. salina in Scottish saltmarshes, where it has recently colonised, shows significantly less clonal reproduction in comparison to the same species in Norway and another long-established, closely related, Scottish species, C. recta. This difference is probably due to population longevity and latitudinal effects.

By comparison no latitudinal or habitat location influences were observed in a study of the balance of sexual and clonal variation in four closely related saltmarsh species (C. paleacea, C. vacillans, C. salina and C. subspathacea). All species show a mix of reproductive mode, as do most populations. It is proposed that individual genets respond to local environmental conditions, specifically habitat longevity and soil characteristics.

Analysis of the recently discovered, taxonomically problematic population of Carex sect. Phacocystis at Bettyhill (Scotland) revealed that C. salina and C. vacillans remain the putative species. The high level of heterozygosity also suggests that the population may be a product of recent hybridisation. Future work of the section may fruitfully include assessing clonal age and structure alongside habitat age. Dispersal techniques distances may also yield interesting results.

Date of Award	2025
Original language	English
Awarding Institution	Edge Hill University
Supervisor	MOHAMED EL MOHTADI (Director of Studies) & ANNE OXBROUGH (Supervisor)