﻿Invasive predators induce plastic and adaptive responses during embryo development in a threatened frog

Mattia Falaschi,Benedetta Barzaghi,Gentile Francesco Ficetola,Raoul Manenti,Martina Muraro,Samuele Romagnoli

doi:10.3897/neobiota.70.65454

Abstract

Invasive predators can strongly affect native populations. If alien predator pressure is strong enough, it can induce anti-predator responses, including phenotypic plasticity of exposed individuals and local adaptations of impacted populations. Furthermore, maternal investment is an additional pathway that could provide resources and improve performance in the presence of alien predators. We investigated the potential responses to an alien predator crayfish (Procambarus clarkii) in a threatened frog (Rana latastei) by combining field observations with laboratory measurements of embryo development rate, to assess the importance of parental investment, origin and exposure to the crayfish cues. We detected a strong variation in parental investment amongst frog populations, but this variation was not related to the invasion status of the site of origin, suggesting that mothers did not modulate parental investment in relation to the presence of alien predators. However, cues of the invasive crayfish elicited plastic responses in clutches and tadpoles development: embryos developed faster when exposed to the predator. Furthermore, embryos from invaded sites reached Gosner’s development stage 25 faster than those from non-invaded sites. This ontogenetic shift can be interpreted as a local adaptation to the alien predator and suggests that frogs are able to recognise the predatory risk. If these plastic responses and local adaptation are effective escape strategies against the invasive predator, they may improve the persistence of native frog populations.

Highlights

Biological invasions are a major threat to biodiversity and exert multiple impacts on the ecosystems on a global scale (Bellard et al 2016, Nentwig et al 2018)
We investigated the potential responses to an alien predator crayfish (Procambarus clarkii) in a threatened frog (Rana latastei) by combining field observations with laboratory measurements of embryo development rate, to assess the importance of parental investment, origin and exposure to the crayfish cues
We detected a strong variation in parental investment amongst frog populations, but this variation was not related to the invasion status of the site of origin, suggesting that mothers did not modulate parental investment in relation to the presence of alien predators

Summary

Introduction

Biological invasions are a major threat to biodiversity and exert multiple impacts on the ecosystems on a global scale (Bellard et al 2016, Nentwig et al 2018). Invasive predators often cause declines and extinctions of native species (Mooney and Cleland 2001) These negative impacts have been often explained by the lack of common evolutionary history, which can hamper predator recognition in native prey and can limit the expression of effective anti-predator responses (Sih et al 2010). If responses to invasive predators are effective, they may increase prey fitness and, can allow long-term persistence of native populations. While the selective pressures exerted by invasive species can promote the quick evolution of behavioural and morphological traits limiting exposure to predation (Skelly and Freidenburg 2000, Melotto et al 2020), there is little information available on the role played by parental investment. The effectiveness of parental investments in allowing native prey species persistence remains an open question

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