Santtu Pentikäinen

Temperature plays a pivotal role in defining the distribution of species and the fitness of individuals within species' ranges. Phenotypic plasticity can allow individuals to cope with varying environmental conditions, including rapid climate change. Populations at range edges experience more variable conditions than core populations and thus are hypothesized to exhibit higher thermal plasticity. However, as the strength of plasticity often varies between individuals, it can also differ among local populations at range edges. We studied the extent of and variation in thermal plasticity for several traits within and between populations of the perennial herb Plantago lanceolata L. (Plantaginaceae) at its northern range edge. We sampled seeds from nine sites within a 50 × 50 km region and grew them under three temperature regimes in a greenhouse. We measured traits related to size, flowering, pathogen responses, and inflorescence pigmentation. We expected to find higher plasticity in traits less strongly connected to fitness and that differences between individuals would outweigh differences between populations in underpinning this variation in plasticity. Our results show thermal plasticity in leaf size and abundance, flowering probability and abundance, and pigmentation. Notably, we also found increased pathogen symptoms and higher infection rates of one of two viruses screened, highlighting the potential for changes in pathogen sensitivity and exposure under climate change. Importantly, in all traits but flower abundance, more variation in plasticity was attributable to differences within populations than between populations. Although this contribution was small in magnitude compared to thermal effects on traits, the higher intra‐ versus interpopulation variation in plasticity suggests that differences between individuals provide most of the variation in thermal plasticity, which may be driven by small‐scale variations in habitat conditions, highlighting the need for conservation strategies that consider microhabitat variation to support short‐term adaptive responses to thermal variability.

While brown rats ( Rattus norvegicus ) are a widely used model species in behavioural studies, not much is known about their behavioural patterns in the wild, despite such populations being common and widespread across the globe. Nevertheless, widely used camera traps can provide much-needed material on the behaviour of not only rats but also many other synanthropic species. To understand rat social behaviour and assess the potential of opportunistically sourced video material, we constructed ethograms and analysed rat behaviour on a site where a colony of rats were supplementally fed to collect material for an art project. Across the nine-month observation period and approximately 2,000 h of video material, we found 222 video clips with more than one rat individual present simultaneously. These clips contained neutral and agonistic behaviours (such as stealing food and chasing), but also affiliative behaviours (smelling and nose touching) and even prosociality (such as play and peaceful sharing of food). Associative behaviour was more common whereas agonistic behaviour was rare. Our results show that even opportunistically collected video material can be used for ethological analysis and can reveal new aspects regarding the behaviour of poorly studied species or contexts.