Abstract:
Diversity in social structures, from solitary to
eusocial, is a prominent feature of subterranean African
mole-rat species. Damaraland mole-rats are eusocial, they
live in colonies that are characterized by a reproductive division
of labor and a subdivision into castes based on physiology
and behavior. Damaraland mole-rats are exceptionally
long lived and reproductive animals show delayed aging
compared to non-reproductive animals. In the present
study, we described the hippocampal architecture and the
rate of hippocampal neurogenesis of wild-derived, adult
Damaraland mole-rats in relation to sex, relative age and
social status or caste. Overall, Damaraland mole-rats were
found to have a small hippocampus and low rates of neurogenesis.
We found no correlation between neurogenesis
and sex or relative age. Social status or caste was the most
prominent modulator of neurogenesis. An inverse relationship
between neurogenesis and social status was apparent,
with queens displaying the lowest neurogenesis while the
worker mole-rats had the most. As there is no natural progression
from one caste to another, social status within a
colony was relatively stable and is reflected in the level of
neurogenesis. Our results correspond to those found in
the naked mole-rat, and may reflect an evolutionary and
environmentally conserved trait within social mole-rat species.
