Celina Burkholz1, Karen Filbee-Dexter1,2, Melinda Coleman1,3,4, and Thomas Wernberg1,2
1Oceans Institute and School of Biological Sciences, University of Western Australia, Crawley, WA, Australia
2Institute of Marine Research, His, Norway
3New South Wales Fisheries, Department of Primary Industries, Coffs Harbour, NSW, Australia
4National Marine Science Centre, Southern Cross University, Coffs Harbour, NSW, Australia
Intraspecific variation is critical in driving adaptation to changing environmental conditions and is driven by local adaptation, genetic diversity and phenotypic plasticity. While differences in mean performance measures are commonly assessed when comparing species and populations, the extent and drivers of intraspecific variation within natural populations remain considerably less well known. Further, the presence of high-performing
individuals within a population may be an indicator of a population’s potential to adapt to a changing climate. In this study we assessed intraspecific variation in performance of two natural Ecklonia radiata populations in Western Australia across annual cycles of environmental conditions. We measured elongation rates and survival of over 400 individuals across two locations over a two-year time period that varied in temperature by ~7 °C. By monitoring tagged individuals, we aimed to evaluate the magnitude of variation within populations through seasons and identify the extent to which high- and low-performing individual are present. Our findings showed that mean elongation rates and variation were correlated, with an increase in both during colder months. While we found differences between individuals with some individuals consistently ranking as high- or low-performing,
there was no clear relationship between higher elongation rates and survival. This study highlights that performance can be used to assess a population’s current state, however, a combination of performance measures is needed to evaluate future performance in a changing climate.