Partitioning along reproductive niche dimensions in sympatric New Zealand freshwater bivalve species
type: CreativeWork
description: Sympatric species of freshwater mussels in the order Unionida may need to partition resources to enable coexistence due to their relatively sedentary life-style and complex symbiotic life-phase dependent on host-fish. Although new data on their reproductive biology is being increasingly documented, particularly in the Northern Hemisphere, major gaps remain in New Zealand where two threatened Hyriidae, Echyridella aucklandica and E. menziesii, can co-occur. This thesis combines multiple approaches to elucidate the reproductive ecology of the previously unstudied E. aucklandica compared to the more widespread E. menziesii, and to examine mechanisms enabling their successful coexistence. I use field and laboratory investigations to compare reproductive niche parameters along three major resource use dimensions: host-fish species, reproductive phenology (time), and habitat use (space), and show that these two sympatric congeneric species have evolved sharply contrasting reproductive strategies. Complex adaptations were identified among the two Echyridella species through contrasting use of larval (glochidia) host-fish infestation strategies and contrasting glochidia morphometry. Female E. aucklandica were found to produce conglutinates, mucus packages containing miniature glochidia thought to lure specific fish to them by resembling fish prey. This is thought to be one of the first Unionida species outside of North America reported to be using functional conglutinates to mimic host diet as an infestation strategy. Miniature glochidia produced by E. aucklandica were around three times smaller than those of E. menziesii, which along with other features such as shape and buoyancy, were consistent with morphological features found in host-specific unionid species elsewhere. For the first time, the brooding phenology of E. aucklandica is reported, filling an important data gap on the basic biology of this poorly known and threatened species. Though E. aucklandica began brood…
abstract: Sympatric species of freshwater mussels in the order Unionida may need to partition resources to enable coexistence due to their relatively sedentary life-style and complex symbiotic life-phase dependent on host-fish. Although new data on their reproductive biology is being increasingly documented, particularly in the Northern Hemisphere, major gaps remain in New Zealand where two threatened Hyriidae, Echyridella aucklandica and E. menziesii, can co-occur. This thesis combines multiple approaches to elucidate the reproductive ecology of the previously unstudied E. aucklandica compared to the more widespread E. menziesii, and to examine mechanisms enabling their successful coexistence. I use field and laboratory investigations to compare reproductive niche parameters along three major resource use dimensions: host-fish species, reproductive phenology (time), and habitat use (space), and show that these two sympatric congeneric species have evolved sharply contrasting reproductive strategies. Complex adaptations were identified among the two Echyridella species through contrasting use of larval (glochidia) host-fish infestation strategies and contrasting glochidia morphometry. Female E. aucklandica were found to produce conglutinates, mucus packages containing miniature glochidia thought to lure specific fish to them by resembling fish prey. This is thought to be one of the first Unionida species outside of North America reported to be using functional conglutinates to mimic host diet as an infestation strategy. Miniature glochidia produced by E. aucklandica were around three times smaller than those of E. menziesii, which along with other features such as shape and buoyancy, were consistent with morphological features found in host-specific unionid species elsewhere. For the first time, the brooding phenology of E. aucklandica is reported, filling an important data gap on the basic biology of this poorly known and threatened species. Though E. aucklandica began brood…
author: Melchior, Michéle
license: https://researchcommons.waikato.ac.nz/bitstreams/ba89b570-5d9a-40f9-ae27-972c6678b014/download
date published: 2021
date modified: 2026-07-24T05:57:27Z
provider: University Waikato
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: The University of Waikato