10.5061/DRYAD.6HP93CD
Benowitz, Kyle M.
University of Arizona
Sparks, Madeline E.
University of Georgia
McKinney, Elizabeth C.
University of Georgia
Moore, Patricia J.
University of Georgia
Moore, Allen J.
University of Georgia
Data from: Variation in mandible development and its relationship to
dependence on parents across burying beetles
Dryad
dataset
2018
National Science Foundation
https://ror.org/021nxhr62
IOS-1354358
2018-11-21T13:35:46Z
2018-11-21T13:35:46Z
en
https://doi.org/10.1002/ece3.4713
16547 bytes
1
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Background: In species with parental care, there is striking variation in
offspring dependence at birth, ranging from feeding independence to
complete dependency on parents for nutrition. Frequently, highly dependent
offspring further evolve reductions or alterations of morphological traits
that would otherwise promote self-sufficiency. Here, we examine evidence
for morphological evolution associated with dependence in burying beetles
(Nicrophorus spp.), in which dependence upon parents appears to have
several independent origins. In many species precocial first instar larvae
can survive without parenting, but several altricial species die at this
stage on their own. We focused specifically on the mandibles, which are
expected to be related to feeding ability and therefore independence from
parents. Results: We find no evidence that the size of the mandible is
related to dependence on parents. However, we do find a developmental and
phylogenetic correlation between independence and the presence of
serrations on the inner edge of the mandible. Mandibles of independent
species bear serrations at hatching, whereas dependent species hatch with
smooth mandibles, only developing serrations in the second instar when
these larvae gain the ability to survive on their own. Phylogenetic
evidence suggests that serrations coincide with independence repeatedly.
We note a single exception to this trend, a beetle with a serrated
mandible that cannot survive without parents. However, this exception
occurs in a species that has recently evolved the loss of independence.
Conclusions: We argue that the absence of mandible serrations occurs due
to alternative selection pressures incurred in larvae dependent upon
parents to survive. We suggest that this may have led to a variable
function for mandibles, perhaps related to increased competitive ability
among siblings or increased efficiency in receiving nutrition from
parents. Furthermore, we propose that the phylogenetic pattern we see is
consistent with the long-held evolutionary hypothesis that evolutionary
change in behavior and physiology precede morphological change.
head capsule and mandible lengthsbenowitz_etal_ece_for_dryad.xlsx