Genetic relationships among Australian Cricotopus

Genetic relationships among Australian Cricotopus


Description

Freshwater biomonitoring is routinely undertaken to infer and monitor the ‘health’ of freshwater ecosystems across the country, particularly in areas impacted by mining. This methodology can benefit from accurately resolved species-level systematics, as decisions regarding so-called ‘indicator’ species are reliant on our understanding of actual biological relationships among closely allied taxa.

In Australia, one group of understudied freshwater taxa of biomonitoring importance is the non-biting midge genus Cricotopus. Australian Cricotopus species inhabit a wide variety of habitat types, from highly degraded coastal streams and man-made drainages to more pristine upland streams. Interestingly, there is much variation among the ecologies of individual species such that some widespread species are highly tolerant of impacted environments, whilst others are highly sensitive and geographically restricted.

Despite the apparent variation in life history traits among species within the genus, the genus is widely included in biomonitoring surveys of water quality, in which the presence of larval Cricotopus in water bodies is often taken to be an indicator of negative impact. This generalisation that all members of the genus are highly tolerant of stream impact appears largely due to our poor understanding of larval morphology among many Australian Cricotopus species. Thus, it is likely that important information concerning stream ‘health’ is being overlooked because accurate species identifications cannot be made for this genus.

This project aims to resolve the knowledge gaps surrounding the relationships among the Australian Cricotopus species by using a combination of molecular and morphological approaches to reconstruct a phylogeny for the Australian Cricotopus. This phylogeny will help target development of diagnostics for identification of larvae and will shed light on the evolution of pollution tolerance in this genus. Coupled with data regarding species ecological tolerances, this data will allow a more holistic view of the potential effect on Cricotopus species of changes to freshwater stream quality in Australia.

Objectives

  • Resolve a phylogeny of Australian Cricotopus species, encompassing all known taxa fully sampled across their distributions to capture potential cryptic diversity.
  • Develop diagnostic morphological and/or molecular characters to aid freshwater biomonitoring programs.
  • Correlate phylogenetic relationships with ecology and habitat preference to investigate the evolution of pollution tolerance.

References

Krosch, M. N. and P. S. Cranston (2013). "Not drowning, (hand)waving? Molecular phylogenetics, biogeography and evolutionary tempo of the ‘gondwanan’ midge Stictocladius Edwards (Diptera: Chironomidae)." Molecular Phylogenetics and Evolution 68(3): 595-603.

Krosch, M. N. and P. S. Cranston (2012). "Non-destructive DNA extraction from Chironomidae, including fragile pupal exuviae, extends analysable collections and enhances vouchering." Chironomus 25: 22-27.

Krosch, M. N., et al. (2011). "Systematics and biogeography of the Gondwanan Orthocladiinae (Diptera: Chironomidae)."Molecular Phylogenetics and Evolution 59(2): 458-468.

Key People