ResurrectedCeriodaphnia quadrangulahighlight differences between pheno- and genotypic expressions

Marko Reinikainen,Emma Åhlén

doi:10.1002/ece3.401

Abstract

The hatching of cladoceran ephippia from a 15-cm long sediment core was investigated, and Ceriodaphnia quadrangula clones were isolated from different sediment layers. Bosmina microfossil data were also analyzed, and compared with the corresponding data from a Pb210 dated core, which allowed us to infer the age of the sediment layers. Using changes in Bosmina microfossil morphologies, we were, furthermore, able to infer the presence of different regimes of fish predation. C. quadrangula was found to hatch in layers with an inferred age of approximately a century. Newly hatched individuals had smaller eye-size in sediment layers corresponding to high predation by young-of-the-year perch. Newly hatched individuals also generally had a marked neck-spine. In contrast, morphological characters of C. quadrangula clones reared in the laboratory over several generations showed no variation in relation to predation regime, indicating the absence of fixed genotype level changes. Furthermore, the laboratory grown clones only rarely produced a neck-spine. The results suggest phenotypic variation in response to the regime under which ephippia were produced.

Highlights

The term “resurrection ecology” has been used to describe an approach where long-lived dormant stages are utilized to study ecological changes over time periods that would be impossible to explore using observations on contemporary populations (Kerfoot et al 1999)
We investigate the viability of ephippia from Ceriodaphnia quadrangula in the sediment of a boreal-forest lake
The data from the dated sediment core established a relationship between fish predation intensity and Bosmina microfossil characteristics in the same basin of the lake

Summary

Introduction

The term “resurrection ecology” has been used to describe an approach where long-lived dormant stages are utilized to study ecological changes over time periods that would be impossible to explore using observations on contemporary populations (Kerfoot et al 1999). Especially cladocerans and some copepods hatched from resting eggs have been successfully employed to study changes in life-history, behavioral, or genetic characteristics in response to varying selective forces (Brendonck and Meester 2003). Cladocerans have a great advantage in experimental work, as parthenogenetic clones can be established. Most of the cladoceran studies have been carried out using Daphnia, which is abundant in many temperate lakes and well-represented in ecological and evolutionary work in general. For instance, been used to show adaptation in resistance to pollution (Kerfoot et al 1999) and cyanobacterial toxins (Hairston et al 1999). Daphnia has been used to understand fitness consequences of hatching and reproduction success (Brede et al 2007), to study changes in the strength of interspecific competition (Steiner et al 2007), and to study the microevolution of diel vertical migration (Michels et al 2007)

Methods

Results

Conclusion