Combining DNA and morphological analyses of faecal samples improves insight into trophic interactions: a case study using a generalist predator
The diet of pinnipeds is most commonly inferred from morphologically diagnostic remains of prey in their scats. Although this method can generate quantitative estimates of diet simply, important prey types may not always be detected. DNA-based methods improve detection of prey in scats, but they are...
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Online Access: | https://eprints.utas.edu.au/4156/ https://eprints.utas.edu.au/4156/1/4156.pdf https://doi.org/10.1007/s00227-007-0732-y |
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ftunivtasmania:oai:eprints.utas.edu.au:4156 2023-05-15T13:36:46+02:00 Combining DNA and morphological analyses of faecal samples improves insight into trophic interactions: a case study using a generalist predator Casper, RM Jarman, SN Gales, NJ Hindell, MA 2007 application/pdf https://eprints.utas.edu.au/4156/ https://eprints.utas.edu.au/4156/1/4156.pdf https://doi.org/10.1007/s00227-007-0732-y en eng Springer https://eprints.utas.edu.au/4156/1/4156.pdf Casper, RM, Jarman, SN, Gales, NJ and Hindell, MA 2007 , 'Combining DNA and morphological analyses of faecal samples improves insight into trophic interactions: a case study using a generalist predator' , Marine Biology, vol. 152, no. 4 , pp. 815-825 , doi:10.1007/s00227-007-0732-y <http://dx.doi.org/10.1007/s00227-007-0732-y>. cc_utas 300802 Wildlife and Habitat Management Article PeerReviewed 2007 ftunivtasmania https://doi.org/10.1007/s00227-007-0732-y 2020-05-30T07:18:00Z The diet of pinnipeds is most commonly inferred from morphologically diagnostic remains of prey in their scats. Although this method can generate quantitative estimates of diet simply, important prey types may not always be detected. DNA-based methods improve detection of prey in scats, but they are not quantitative. While some studies have combined morphological and DNA-based methods, these have only assessed prey that are represented by their hard remains in scats. To overcome this bias, we apply molecular and morphological analyses to the soft and hard portions of faecal samples respectively, to estimate the diet of lactating Antarctic fur seals (Arctocephalus gazella) on Heard Island. The diet of this population is of particular interest because it is expanding rapidly and may rely to some extent on mackerel icefish (Champsocephalus gunnari), which are subject to commercial fisheries. Based on results from morphological analysis and likely important prey types, we tested for DNA remains of C. gunnari, myctophids and squid in faecal samples. The proportion of samples (n = 54) yielding no dietary information was reduced from around 25.9% using either method alone, to 9.3% when combined. Detection of all prey types tested for was notably improved by integrating molecular and morphological data. Data from either method alone would have underestimated the number of animals consuming C. gunnari by around 25.7%. Detection of multiple prey types in samples increased from 9.3% when using morphological analysis only, to 33.3% when using DNA only, to 46.3% when using both methods. Taken in isolation, morphological data inferred that individual seals consume either C. gunnari or myctophids, probably foraging in separate locations characteristic of those prey. Including molecular data demonstrated that while this may be true of some individuals, many other seals consume a mixed diet of at least C. gunnari, myctophids and squid. This new approach of combining DNA-based and morphological analyses of diet samples markedly increased the number of samples yielding dietary information, as well as increasing the amount of information attained from those samples. Our findings illustrate the broad potential of this technique to improve insight into trophic interactions in marine ecosystems. Article in Journal/Newspaper Antarc* Antarctic Antarctic Fur Seals Arctocephalus gazella Heard Island Icefish University of Tasmania: UTas ePrints Antarctic Heard Island Marine Biology 152 4 815 825 |
institution |
Open Polar |
collection |
University of Tasmania: UTas ePrints |
op_collection_id |
ftunivtasmania |
language |
English |
topic |
300802 Wildlife and Habitat Management |
spellingShingle |
300802 Wildlife and Habitat Management Casper, RM Jarman, SN Gales, NJ Hindell, MA Combining DNA and morphological analyses of faecal samples improves insight into trophic interactions: a case study using a generalist predator |
topic_facet |
300802 Wildlife and Habitat Management |
description |
The diet of pinnipeds is most commonly inferred from morphologically diagnostic remains of prey in their scats. Although this method can generate quantitative estimates of diet simply, important prey types may not always be detected. DNA-based methods improve detection of prey in scats, but they are not quantitative. While some studies have combined morphological and DNA-based methods, these have only assessed prey that are represented by their hard remains in scats. To overcome this bias, we apply molecular and morphological analyses to the soft and hard portions of faecal samples respectively, to estimate the diet of lactating Antarctic fur seals (Arctocephalus gazella) on Heard Island. The diet of this population is of particular interest because it is expanding rapidly and may rely to some extent on mackerel icefish (Champsocephalus gunnari), which are subject to commercial fisheries. Based on results from morphological analysis and likely important prey types, we tested for DNA remains of C. gunnari, myctophids and squid in faecal samples. The proportion of samples (n = 54) yielding no dietary information was reduced from around 25.9% using either method alone, to 9.3% when combined. Detection of all prey types tested for was notably improved by integrating molecular and morphological data. Data from either method alone would have underestimated the number of animals consuming C. gunnari by around 25.7%. Detection of multiple prey types in samples increased from 9.3% when using morphological analysis only, to 33.3% when using DNA only, to 46.3% when using both methods. Taken in isolation, morphological data inferred that individual seals consume either C. gunnari or myctophids, probably foraging in separate locations characteristic of those prey. Including molecular data demonstrated that while this may be true of some individuals, many other seals consume a mixed diet of at least C. gunnari, myctophids and squid. This new approach of combining DNA-based and morphological analyses of diet samples markedly increased the number of samples yielding dietary information, as well as increasing the amount of information attained from those samples. Our findings illustrate the broad potential of this technique to improve insight into trophic interactions in marine ecosystems. |
format |
Article in Journal/Newspaper |
author |
Casper, RM Jarman, SN Gales, NJ Hindell, MA |
author_facet |
Casper, RM Jarman, SN Gales, NJ Hindell, MA |
author_sort |
Casper, RM |
title |
Combining DNA and morphological analyses of faecal samples improves insight into trophic interactions: a case study using a generalist predator |
title_short |
Combining DNA and morphological analyses of faecal samples improves insight into trophic interactions: a case study using a generalist predator |
title_full |
Combining DNA and morphological analyses of faecal samples improves insight into trophic interactions: a case study using a generalist predator |
title_fullStr |
Combining DNA and morphological analyses of faecal samples improves insight into trophic interactions: a case study using a generalist predator |
title_full_unstemmed |
Combining DNA and morphological analyses of faecal samples improves insight into trophic interactions: a case study using a generalist predator |
title_sort |
combining dna and morphological analyses of faecal samples improves insight into trophic interactions: a case study using a generalist predator |
publisher |
Springer |
publishDate |
2007 |
url |
https://eprints.utas.edu.au/4156/ https://eprints.utas.edu.au/4156/1/4156.pdf https://doi.org/10.1007/s00227-007-0732-y |
geographic |
Antarctic Heard Island |
geographic_facet |
Antarctic Heard Island |
genre |
Antarc* Antarctic Antarctic Fur Seals Arctocephalus gazella Heard Island Icefish |
genre_facet |
Antarc* Antarctic Antarctic Fur Seals Arctocephalus gazella Heard Island Icefish |
op_relation |
https://eprints.utas.edu.au/4156/1/4156.pdf Casper, RM, Jarman, SN, Gales, NJ and Hindell, MA 2007 , 'Combining DNA and morphological analyses of faecal samples improves insight into trophic interactions: a case study using a generalist predator' , Marine Biology, vol. 152, no. 4 , pp. 815-825 , doi:10.1007/s00227-007-0732-y <http://dx.doi.org/10.1007/s00227-007-0732-y>. |
op_rights |
cc_utas |
op_doi |
https://doi.org/10.1007/s00227-007-0732-y |
container_title |
Marine Biology |
container_volume |
152 |
container_issue |
4 |
container_start_page |
815 |
op_container_end_page |
825 |
_version_ |
1766083742665801728 |