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Sexual dimorphism and allometry in the sphecophilous rove beetle Triacrus dilatus.

Marlowe MH, Murphy CA, Chatzimanolis S - PeerJ (2015)

Bottom Line: Linear regressions were run to examine if there were significant relationships between the different measurements.Our results indicated that males had significantly larger mandibles and ocular distances than females, but the overall body length was not significantly different between the sexes.We found no evidence of major and minor forms in either sex.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biological and Environmental Sciences, University of Tennessee at Chattanooga , Chattanooga, TN , USA.

ABSTRACT
The rove beetle Triacrus dilatus is found in the Atlantic forest of South America and lives in the refuse piles of the paper wasp Agelaia vicina. Adults of T. dilatus are among the largest rove beetles, frequently measuring over 3 cm, and exhibit remarkable variation in body size. To examine sexual dimorphism and allometric relationships we measured the length of the left mandible, ocular distance and elytra. We were interested in determining if there are quantifiable differences between sexes, if there are major and minor forms within each sex and if males exhibit mandibular allometry. For all variables, a t-test was run to determine if there were significant differences between the sexes. Linear regressions were run to examine if there were significant relationships between the different measurements. A heterogeneity of slopes test was used to determine if there were significant differences between males and females. Our results indicated that males had significantly larger mandibles and ocular distances than females, but the overall body length was not significantly different between the sexes. Unlike most insects, both sexes showed positive linear allometric relationships for mandible length and head size (as measured by the ocular distance). We found no evidence of major and minor forms in either sex.

No MeSH data available.


Related in: MedlinePlus

Scatter plot and linear regression between ocular distance and left mandible for males and females.N = 29 males; N = 22 females.
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fig-4: Scatter plot and linear regression between ocular distance and left mandible for males and females.N = 29 males; N = 22 females.

Mentions: Linear regression analyses showed that every relationship was significant and positive (Table 1 and Figs. 3–5). When comparing the linear regressions between males and females for elytra length vs. left mandible, we found that both the slopes and intercepts for the relationships were not significantly different from one another (Table 2 and Fig. 3). The same was found when comparing males and females for ocular distance vs. left mandible; there were no significant differences between the two (Table 2 and Fig. 4). However, when examining elytra length vs. ocular distance, males had a significantly larger slope than the females (intercepts were not significantly different) (Table 2 and Fig. 5). This indicates that for equal increases in elytra length (or body length), males would have a larger increase in ocular distance than females.


Sexual dimorphism and allometry in the sphecophilous rove beetle Triacrus dilatus.

Marlowe MH, Murphy CA, Chatzimanolis S - PeerJ (2015)

Scatter plot and linear regression between ocular distance and left mandible for males and females.N = 29 males; N = 22 females.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4525698&req=5

fig-4: Scatter plot and linear regression between ocular distance and left mandible for males and females.N = 29 males; N = 22 females.
Mentions: Linear regression analyses showed that every relationship was significant and positive (Table 1 and Figs. 3–5). When comparing the linear regressions between males and females for elytra length vs. left mandible, we found that both the slopes and intercepts for the relationships were not significantly different from one another (Table 2 and Fig. 3). The same was found when comparing males and females for ocular distance vs. left mandible; there were no significant differences between the two (Table 2 and Fig. 4). However, when examining elytra length vs. ocular distance, males had a significantly larger slope than the females (intercepts were not significantly different) (Table 2 and Fig. 5). This indicates that for equal increases in elytra length (or body length), males would have a larger increase in ocular distance than females.

Bottom Line: Linear regressions were run to examine if there were significant relationships between the different measurements.Our results indicated that males had significantly larger mandibles and ocular distances than females, but the overall body length was not significantly different between the sexes.We found no evidence of major and minor forms in either sex.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biological and Environmental Sciences, University of Tennessee at Chattanooga , Chattanooga, TN , USA.

ABSTRACT
The rove beetle Triacrus dilatus is found in the Atlantic forest of South America and lives in the refuse piles of the paper wasp Agelaia vicina. Adults of T. dilatus are among the largest rove beetles, frequently measuring over 3 cm, and exhibit remarkable variation in body size. To examine sexual dimorphism and allometric relationships we measured the length of the left mandible, ocular distance and elytra. We were interested in determining if there are quantifiable differences between sexes, if there are major and minor forms within each sex and if males exhibit mandibular allometry. For all variables, a t-test was run to determine if there were significant differences between the sexes. Linear regressions were run to examine if there were significant relationships between the different measurements. A heterogeneity of slopes test was used to determine if there were significant differences between males and females. Our results indicated that males had significantly larger mandibles and ocular distances than females, but the overall body length was not significantly different between the sexes. Unlike most insects, both sexes showed positive linear allometric relationships for mandible length and head size (as measured by the ocular distance). We found no evidence of major and minor forms in either sex.

No MeSH data available.


Related in: MedlinePlus