Age dependent costs of reproduction in a sexually dimorphic species : male fallow deer as an example
Energy and time are two of the most important factors limiting the investment spent on reproduction for an organism. Due to this limitation, individuals have to balance between using energy for maintenance or growth and using it for reproduction. In many polygynous male mammals, reproduction h...
| Autor principal: | |
|---|---|
| Formato: | H2 |
| Lenguaje: | Inglés sueco |
| Publicado: |
SLU/Dept. of Ecology
2017
|
| Materias: |
| _version_ | 1855571829630959616 |
|---|---|
| author | Lindström, Linn |
| author_browse | Lindström, Linn |
| author_facet | Lindström, Linn |
| author_sort | Lindström, Linn |
| collection | Epsilon Archive for Student Projects |
| description | Energy and time are two of the most important factors limiting the investment spent on reproduction
for an organism. Due to this limitation, individuals have to balance between using energy for
maintenance or growth and using it for reproduction. In many polygynous male mammals, reproduction
has been pointed out to be the most energetically costly time of the year and in sexually size
dimorphic species mortality is sex-biased toward the larger sex. Fallow deer is a polygynous,
seasonally breeding species demonstrating a high level of sexual size dimorphism where males can be
double the size of females. During the breeding season, males compete for females and display on
the breeding site. Behaviours like fighting, vocalization and a reduction in forage intake can be
very costly and males often loose a large amount of weight.
In this study, I estimate the cost of reproduction by using culling data together with
movement data collected from wild GPS-marked male fallow deer. I compare timing of body mass- and
bone marrow fat loss with daily average movements and home range sizes between different age
classes during time of rut. Mature males (≥ 4-years-old) lost on average 24% of their body mass
during pre- and post-rut and had a decline in bone marrow fat of approx. 20%. Simultaneously,
younger males (≤ 2-years-old) lost much less, if anything. Additionally, males 1 – 2-years-old had
the highest mobility during rut while 4 year- and older ones moved least. There were no significant
differences in home range sizes between mature and immature males and of all seasons was autumn the
season with largest home range sizes, highly influenced by the time of rut. These results suggest
that the loss in body mass is not due to a higher mobility during rut and the distinct decline in
both body mass and bone marrow fat indicates a large investment into reproduction in mature males.
Finally, as far as I know, there are no previous published studies ever of male fallow deer home
range sizes, based on GPS-data, making this study unique from that perspective. |
| format | H2 |
| id | RepoSLU11213 |
| institution | Swedish University of Agricultural Sciences |
| language | Inglés swe |
| publishDate | 2017 |
| publishDateSort | 2017 |
| publisher | SLU/Dept. of Ecology |
| publisherStr | SLU/Dept. of Ecology |
| record_format | eprints |
| spelling | RepoSLU112132018-09-26T12:20:52Z Age dependent costs of reproduction in a sexually dimorphic species : male fallow deer as an example Lindström, Linn dama dama cost of reproduction home range size sexual dimorphism Energy and time are two of the most important factors limiting the investment spent on reproduction for an organism. Due to this limitation, individuals have to balance between using energy for maintenance or growth and using it for reproduction. In many polygynous male mammals, reproduction has been pointed out to be the most energetically costly time of the year and in sexually size dimorphic species mortality is sex-biased toward the larger sex. Fallow deer is a polygynous, seasonally breeding species demonstrating a high level of sexual size dimorphism where males can be double the size of females. During the breeding season, males compete for females and display on the breeding site. Behaviours like fighting, vocalization and a reduction in forage intake can be very costly and males often loose a large amount of weight. In this study, I estimate the cost of reproduction by using culling data together with movement data collected from wild GPS-marked male fallow deer. I compare timing of body mass- and bone marrow fat loss with daily average movements and home range sizes between different age classes during time of rut. Mature males (≥ 4-years-old) lost on average 24% of their body mass during pre- and post-rut and had a decline in bone marrow fat of approx. 20%. Simultaneously, younger males (≤ 2-years-old) lost much less, if anything. Additionally, males 1 – 2-years-old had the highest mobility during rut while 4 year- and older ones moved least. There were no significant differences in home range sizes between mature and immature males and of all seasons was autumn the season with largest home range sizes, highly influenced by the time of rut. These results suggest that the loss in body mass is not due to a higher mobility during rut and the distinct decline in both body mass and bone marrow fat indicates a large investment into reproduction in mature males. Finally, as far as I know, there are no previous published studies ever of male fallow deer home range sizes, based on GPS-data, making this study unique from that perspective. Tid och energi är två av de viktigaste faktorerna vilka begränsar en organisms möjlighet att reproducera sig. På grund av denna begränsning tvingas individerna balansera sin energiförbrukning mellan att använda den för överlevnad och kroppstillväxt eller till reproduktion. Parningstiden eller brunsten har pekats ut som den mest energikrävande perioden på året hos hanar som parar sig med många honor (polygami). Hos arter där graden av polygami är hög – dvs då vissa hanar parar sig med väldigt många honor och andra inte lyckas para sig alls, är det ofta även stor skillnad i storlek mellan könen. Kanske på grund av den höga konkurrensen om parningar och dödligheten i anslutning till brunsten är då ofta riktad mot det större könet. Dovhjort är en polygam art vilken förökar sig under en specifik period på året. I Sverige inträffar högbrunsten oftast i oktober. Hos arten finns en tydlig storleksskillnad mellan könen, så kallad könsdimorfi, där hanarna kan bli dubbelt så stora som honorna. Under parningssäsongen tävlar hanarna mot varandra och visar upp sig på specifika parningsområden kallade brunstplatser. Den starkaste och mest dominanta hanen är den som får para sig med flest honor. Beteenden som slagsmål, brölande och minskat födointag tycks vara väldigt kostsamma och hanar tappar ofta mycket vikt under brunstperioden. En på året sen brunst, den kraftiga viktnedgången och en mycket begränsad tid för fysisk återhämtning innan kommande vinter kan vara förödande och i värsta fall leda till döden. I den här studien uppskattar jag den fysiologiska kostnaden för brunsten genom att använda avskjutningsdata tillsammans med rörelsedata från GPS-märkta, vilda, dovhjortar. Datat är insamlad på Koberg egendoms marker i Västergötland under nio år (2006 – 2015). Brunsten definierades här på individnivå via de GPS-märkta handjuren till den period då de gick till- respektive lämnade sin brunstplats. Under åren 2007 – 2011 inföll brunsten på Koberg i genomsnitt 27 september till 8 november, med variationen 15 dagar för vardera början och slut. Genomsnittligen både startade och avslutade de yngre hanarna (2 år) brunsten senare än de äldre hanarna (≥ 3 år). Handjurens viktnedgång och förändringar i halten benmärgsfett jämförs i tid med förändringen i daglig genomsnittlig förflyttning och djurens hemområdesstorlek för olika åldersgrupper under brunstperioden. De yngsta handjuren, 1 – 2 år gamla, rörde sig mest under brunsten medan de äldre hanarna, 4 år och äldre, rörde sig minst. Trots detta tappade de äldre handjuren (≥ 4 år) i genomsnitt 24% av sin kroppsvikt under brunsten och förlorade cirka 20% benmärgsfett. Under samma period tappade de yngre hanarna (≤ 2 år) inte alls lika mycket, om ens något. Däremot hittades inga statistiskt signifikanta skillnader i hemområdesstorlekar mellan äldre och yngre handjur. Under hösten var hemområdesstorlekarna som störst, vilket var starkt påverkat av brunstperioden. Dessa resultat antyder att viktnedgången inte beror på att de vuxna hjortarna rör sig mer under brunsten utan avmagring och sjunkande benmärgsfett tyder på att de äldre hanarna lägger stora resurser på parningen och sannolikt inte kompenserar detta med ett ökat födointag. Slutligen, vad jag vet finns inga tidigare publicerade studier på dovhjortshanars hemområdesstorlekar baserade på GPS-data, vilket gör denna studie unik ur det perspektivet. SLU/Dept. of Ecology 2017 H2 eng swe https://stud.epsilon.slu.se/11213/ |
| spellingShingle | dama dama cost of reproduction home range size sexual dimorphism Lindström, Linn Age dependent costs of reproduction in a sexually dimorphic species : male fallow deer as an example |
| title | Age dependent costs of reproduction in a sexually dimorphic species : male fallow deer as an example |
| title_full | Age dependent costs of reproduction in a sexually dimorphic species : male fallow deer as an example |
| title_fullStr | Age dependent costs of reproduction in a sexually dimorphic species : male fallow deer as an example |
| title_full_unstemmed | Age dependent costs of reproduction in a sexually dimorphic species : male fallow deer as an example |
| title_short | Age dependent costs of reproduction in a sexually dimorphic species : male fallow deer as an example |
| title_sort | age dependent costs of reproduction in a sexually dimorphic species : male fallow deer as an example |
| topic | dama dama cost of reproduction home range size sexual dimorphism |