Altitude and latitude have different effects on population characteristics of the widespread plant Anthyllis vulneraria

Abstract

Widespread plants may provide natural models for how population processes change with temperature and other environmental variables and how they may respond to global change. Similar changes in temperature can occur along altitudinal and latitudinal gradients, but hardly any study has compared the effects of the two types of gradients. We studied populations of Anthyllis vulneraria along a latitudinal gradient from Central Europe to the range limit in the North and an altitudinal gradient in the Alps from 500 m to the altitudinal limit at 2500 m, both encompassing a change in annual mean temperature of c. 11.5 °C. Plant size and reproduction decreased, but plant density increased along both gradients, indicating higher recruitment and demographic compensation among vital rates. Our results support the view that demographic compensation may be common in widespread species in contrast to the predictions of the abundant centre model of biogeography. Variation in temperature along the gradients had the strongest effects on most population characteristics, followed by that in precipitation, solar radiation, and soil nutrients. The proportion of plants flowering, seed set and seed mass declined with latitude, while the large variation in these traits along the altitudinal gradient was not related to elevation and covarying environmental variables like annual mean temperature. This suggests that it will be more difficult to draw conclusions about the potential impacts of future climate warming on plant populations in mountains, because of the importance of small-scale variation in environmental conditions.

Genetic diversity and differentiation of populations of Anthyllis vulneraria along elevational and latitudinal gradients

“…However, the ACM assumes that the lower genetic diversity and stronger differentiation among peripheral populations is due to less favorable conditions, which lead to smaller and more isolated populations and subsequently to genetic erosion and strong differentiation (Eckert et al, 2008 ; Hardie & Hutchings, 2010 ; Sexton et al, 2009 ). In contrast, in A. vulneraria the size of populations increased with latitude indicating favorable conditions in the north (Daco et al, 2021 ), and genetic variation was not related to current population size. This suggest that not current conditions resulting in fragmentation, but historical processes (colonization after the ice age) are responsible for the much lower genetic diversity of northern populations.…”

“…This is in contrast to the predictions of the ACM that genetic erosion in small populations would lead to reduced genetic diversity in high elevation populations. However, in A. vulneraria the size of populations actually increased with elevation in the Alps (Daco et al, 2021 ) and one might thus have even expected an increase of genetic diversity with elevation, but no relationship was found. No change of genetic diversity with elevation has also been found in several other studies (Pluess & Stöcklin, 2004 ; see review of Hahn et al ( 2012 ) and Ohsawa & Ide ( 2008 )).…”

“…Jansen et al, 2019 ). The flowers of A. vulneraria are grouped in heads and seed mass varies between 1.9 and 4.0 mg across the studied distribution range (Daco et al, 2021 ). A. vulneraria has been found to be auto‐ or xenogamous in different populations (Couderc, 1971 ; Navarro, 1999 ).…”

“…The large distribution of A. vulneraria allowed us to study general genetic patterns that cannot be detected in arctic‐alpine species or in rare species with fragmented and isolated populations. We studied the genetic diversity and structure of A. vulneraria along two gradients chosen to correspond to a change of 11.5°C in annual mean temperature: a latitudinal gradient of c. 2400 km from Central Europe to Iceland and northern Norway and three elevational gradients of c. 2000 m elevational difference in the European Alps (see also Daco et al, 2021 ). The latitudinal gradient ranged from the centre of the distribution of A. vulneraria to its northern range limit and the elevational gradient in the Alps from the valleys to the upper elevational edge of its distribution.…”

The role of demographic compensation in stabilising marginal tree populations in North America

“…Perfect ‘compensation’ of some vital rates can yield stable population size at marginal populations. Even if imperfect, compensation may reduce overall variation in λ across the species’ range (Daco et al, 2021; Oldfather & Ackerly, 2019) or over time (Andrello et al, 2020; Compagnoni et al, 2016), potentially allowing populations to persist at low latitudinal or elevational edges of a species’ range. Nevertheless, several recent studies have challenged the view that demographic compensation rescues marginal populations (Sheth & Angert, 2018) due to negligible (Dibner et al, 2019; Reed et al, 2021) or even negative (Oldfather et al, 2021) effects on λ.…”