Skip to main content
Dryad logo

Home range use in the West Australian seahorse Hippocampus subelongatus is influenced by sex and partner’s home range but not by body size or paired status

Citation

Kvarnemo, Charlotta et al. (2021), Home range use in the West Australian seahorse Hippocampus subelongatus is influenced by sex and partner’s home range but not by body size or paired status, Dryad, Dataset, https://doi.org/10.5061/dryad.w9ghx3fnz

Abstract

These data and scripts form the basis for Kvarnemo C, Andersson SE, Elisson J, Moore GI and Jones AG (2021). Home range use in the West Australian seahorse Hippocampus subelongatus is influenced by sex and partner's home range but not by body size or paired status. Journal of Ethology 39: 235–248. https://doi.org/10.1007/s10164-021-00698-y. The abstract below is from this paper:

Genetic monogamy is the rule for many species of seahorse, including the West Australian seahorse Hippocampus subelongatus. In this paper, we revisit mark-recapture and genetic data of H. subelongatus, allowing a detailed characterization of movement distances, home range sizes and home range overlaps for each individual of known sex, paired status (paired or unpaired) and body size. As predicted, we find that females have larger home ranges and move greater distances compared to males. We also confirm our prediction that the home ranges of pair-bonded individuals (members of a pair known to reproduce together) overlap more on average than home ranges of randomly chosen individuals of the opposite or same sex. Both sexes, regardless of paired status, had home ranges that overlapped with, on average, 6–10 opposite-sex individuals. The average overlap area among female home ranges was significantly larger than the overlap among male home ranges, probably reflecting females having larger home ranges combined with a female biased adult sex ratio. Despite a prediction that unpaired individuals would need to move around to find a mate, we find no evidence that unpaired members of either sex moved more than paired individuals of the same sex. We also find no effect of body size on home range size, distance moved or number of other individuals with which a home range overlapped. These patterns of movement and overlap in home ranges among individuals of both sexes suggest that low mate availability is not a likely explanation for the maintenance of monogamy in the West Australian seahorse.

Methods

The study was conducted in coastal Western Australia in January-March 1999. It is a mark-recapture study of the West Australian seahorse using SCUBA diving around 25 pylons of a jetty and 82 stumps of a demolished jetty, at a depth of 3-10 m. Diving 2-5 times per week allowed us to map positions of 103 tagged seahorses. Here we excluded individuals seen only once, thus the home range use of 90 individuals was analysed. We provide the following files:

[A_Seahorse_HomeRangeUse.csv] <contains comma separated raw data on home range use>
[B_Seahorse_HomeRange_Positions.txt] <contains tab separated raw data on positions>
[C_Seahorse_Overlaps_Python.py] <contains script in Python for estimating home range overlaps>
[D_Seahorse_Overlaps.csv] <contains comma separated raw data on home range overlaps>
[E_Seahorse_Permutation.R] <contains script in R for a permutation test to compare home range overlaps among females and males>

The collected data of positions (file B) allowed us to calculate number of sightings, home range area (m2) and distance moved (m) (file A). Home range area and the number of other individuals a home range overlapped with (one or both sexes) were extracted using the software Biotas 2.0 (data file not provided here) and included in file A. Based on  file B, areas of home range overlaps were calculated using a custom written script in Python (file C). Based on the resulting data file (D) of home range overlaps between all individuals, a custom written script in R (E) allowed us to use a permutation test to compare extent of home range overlaps depending on sex and paired status.

As explained in greater detail in Kvarnemo et al. (2007, in press), paired status was determined for males based on if the individual was ever seen pregnant, whereas for females it was based on if her genotype (microsatellite DNA) matched the genotype of a sampled brood carried by any of the mated males. Mated pairs were inferred using the same method, with the limitation that not all broods were successfully sampled, or could be matched to a known female. All sampled males showed monogamy within a brood. In file A, monogamy or polygamy refer to mating pattern between broods and was determined for individuals for which we had data from two or more breeding events. 

For all further details on analysis of home range use, see: Kvarnemo, C, Andersson, S, Elisson, J, Moore, GI & AG Jones (2021). Home range use in the West Australian seahorse Hippocampus subelongatus is influenced by sex and partner’s home range but not by body size or paired status. Journal of Ethology 39: 235–248. https://doi.org/10.1007/s10164-021-00698-y.

For additional details on determination of parentage and paired status, see: Kvarnemo, C, Moore, GI, Jones, AG (2007). Sexually selected females in the monogamous Western Australian seahorse Hippocampus subelongatus. Proceedings of the Royal Society B, 274: 521-525. https://doi.org/10.1098/rspb.2006.3753

Usage Notes

For usage, please see: KVARNEMO_WestAustralianSeahorseHomeRangeUse_Readme

Funding

Vetenskapsrådet, Award: B1187/1999

Vetenskapsrådet, Award: 621-2005-4925

Magnus Bergvalls Stiftelse

United States Science Support Program, Award: DEB-9804247

University of Gothenburg