POPULATION GENOMICS, DISTRIBUTION AND REPRODUCTIVE ECOLOGY OF AN ITALIAN STENO-ENDEMIC CHASMOPHYTE, CAMPANULA RAINERI
type: CreativeWork
description: Plant species distributions are the result of climatic and evolutionary histories. Range restriction in steno-endemic species often results from climate oscillations that have reduced the extent of suitable habitat or limited species dispersion across ecological barriers. Narrow endemics may also be of recent origin (yet to disperse) or relicts of ancient lineages. High-elevation environments tend to be rich in endemism as a result of complex climatic histories (underpinning speciation events) and the survival of relicts. Mountain species typically experience extreme conditions and significant temperature changes across short spatial gradients and timeframes, and are particularly sensitive to climate fluctuations, especially on exposed substrates such as rocky faces and screes. Consequently, mountain chasmophytes (i.e. rupestral plant species), are often range-restricted, characterised by small and fragmented populations. The current thesis aims to better understand the causes and consequences of rarity and predict the possibilities for future conservation of a model chasmophyte species, Campanula raineri Perp. (Campanulaceae), a tetraploid steno-endemic of the Italian Prealps, by addressing the following hypotheses: 1) Polyploidy (chromosome set duplication) is a principle driver for the emergence of new endemics. A global-scale analysis of 4210 species representing the principal clades of angiosperms addressed the relationships between chromosome number, geographic distribution and taxon age (Chapter 2). Polyploidy was shown to be a key driver of endemism in angiosperms, with a significant negative exponential relationship between the maximum number of chromosomes and taxon age (R2adj = 0.49, p < 10-4), and greater maximum chromosome numbers (2n = 164 vs. 111) declining more rapidly with taxon age (decay constant = 0.12 vs. 0.04) compared to non-endemics. 2) The genetic structure of C. raineri populations is consistent with changes in habitat suitability throughou…
abstract: Plant species distributions are the result of climatic and evolutionary histories. Range restriction in steno-endemic species often results from climate oscillations that have reduced the extent of suitable habitat or limited species dispersion across ecological barriers. Narrow endemics may also be of recent origin (yet to disperse) or relicts of ancient lineages. High-elevation environments tend to be rich in endemism as a result of complex climatic histories (underpinning speciation events) and the survival of relicts. Mountain species typically experience extreme conditions and significant temperature changes across short spatial gradients and timeframes, and are particularly sensitive to climate fluctuations, especially on exposed substrates such as rocky faces and screes. Consequently, mountain chasmophytes (i.e. rupestral plant species), are often range-restricted, characterised by small and fragmented populations. The current thesis aims to better understand the causes and consequences of rarity and predict the possibilities for future conservation of a model chasmophyte species, Campanula raineri Perp. (Campanulaceae), a tetraploid steno-endemic of the Italian Prealps, by addressing the following hypotheses: 1) Polyploidy (chromosome set duplication) is a principle driver for the emergence of new endemics. A global-scale analysis of 4210 species representing the principal clades of angiosperms addressed the relationships between chromosome number, geographic distribution and taxon age (Chapter 2). Polyploidy was shown to be a key driver of endemism in angiosperms, with a significant negative exponential relationship between the maximum number of chromosomes and taxon age (R2adj = 0.49, p < 10-4), and greater maximum chromosome numbers (2n = 164 vs. 111) declining more rapidly with taxon age (decay constant = 0.12 vs. 0.04) compared to non-endemics. 2) The genetic structure of C. raineri populations is consistent with changes in habitat suitability throughou…
author: VILLA, SARA
language: eng
keywords: Adaptive radiation · Altitude · Climate change response · Conservation · Reproductive isolation · Species Distribution Models, Settore BIO/03 - Botanica Ambientale e Applicata
date published: 2023-04-21
date modified: 2026-07-27T20:19:05Z
provider: Università degli Studi di Milano
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Università degli Studi di Milano

PropertyValue
property ID: Handle
value: https://hdl.handle.net/2434/962757

PropertyValue
property ID: DOI
value: 10.13130/villa-sara_phd2023-04-21