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| Author(s): |
Iago Bueno da Silva
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Rio Claro. 2019-03-15. |
| Institution: | Universidade Estadual Paulista (Unesp). Instituto de Biociências. Rio Claro |
| Defense date: | 2019-02-18 |
| Advisor: | Ana Maria Costa Leonardo |
| Abstract | |
Recent investigations have shown a new perspective concerning the termite reproduction, although many questions remain answered, principally in the Neotropical representatives of the family Termitidae. The development of neotenic reproductives in some species within Isoptera is well stablished, but the development and reproductive contribution of the ergatoid neteonics, which differentiate from workers, are still unknown. Nasutitermes aquilinus, a Neotropical species investigated in the present study, usually develops ergatoid reproductives after the death of the royal couple. However, previous investigations available for N. aquilinus are limited to morphological descriptions of these reproductives. Thus, the objective of the present study was to investigate the reproductive and genetic structure involving ergatoid reproductives in N. aquilinus, using microsatellite and mitochondrial markers. Additionally, morphological and histological analyses were performed to evaluate the presence of imaginal characteristics, maturation of the reproductive organs, type of fat body, and presence of spermatozoa inside the spermatheca of the ergatoid females. In total, 258 individuals from 11 nests, including 43 ergatoid females, were genotyped using five microsatellite loci. The mitochondrial gene COI was sequenced in all the ergatoid neotenics, aiming to identify the matrilines present in the colonies. The ergatoid females presented different physogastry rate and some imaginal traits. Histological sections of the abdomen of ergatoid females showed oocytes in different stages, including terminal vitellogenic oocytes, along with spherical and aflagellate spermatozoa inside the spermatheca. According to the molecular analyses, nine colonies of N. aquilinus were classified into simple families, with alleles and genotypes consistent with monogamy. The nests N2, N6 (both with sampled ergatoids) and N3 (with ergatoids absent) presented genotypes inconsistent with a single pair of reproductives, thus these colonies were classified as possible extended families. Mixed families, which present unrelated reproductives, were not identified for N. aquilinus, due the presence of no more than four alleles per nest. However, the low allele diversity may have obfuscated the occurrence of mixed families. The F-statistics (FIS, FIT, FST) pointed a low inbreeding rate and high genetic diversity, even in colonies classified as possible extended families (N2, N3 and N6), which generally suffer the loss of genetic diversity due a reproductive system involving related individuals. Therefore, it is possible that those colonies present simple cycles of inbreeding, and the genetic diversity and endogamy rate do not follow the values usually observed in extended families. In the colonies N11, the genotypes indicated a breeding system involving only a pair of reproductives, although ergatoide females from these nests presented spermatozoa in the spermatheca and terminal vitellogenic oocytes. In this case, it is suggested that the ergatoid females from this nest have just started their first oviposition cycle, or their offspring was not genotyped in our genetic analyses. (AU) | |
| FAPESP's process: | 17/04525-1 - Reproductive strategies of the neotropical termite Nasutitermes aquilinus (Isoptera: Termitidae) |
| Grantee: | Iago Bueno da Silva |
| Support Opportunities: | Scholarships in Brazil - Master |