Pliocene and Pleistocene events shaping the genetic diversity within the central corridor of the Brazilian Atlantic Forest

Dinoponera lucida (Formicidae; Ponerinae) is an extinction‐threatened species of ant which is endemic in the central corridor of the Atlantic Forest. We used mitochondrial sequences of the Cox1, Cox2 and Cytb genes in order to infer some aspects of the evolutionary history and phylogeography of this ant. High genetic divergence and population structure were observed for the whole species. The current pattern of D. lucida diversity seems to be shaped during different geological times: middle Pliocene, early Pleistocene and mainly late Pleistocene, when the reduction of populations generated a structure pattern of the genetic variation of this species. Our data show that this structure results from the maintenance of populations of D. lucida within very small putative refuges to the south of the central Bahia refugium. We thus argue that, for some Atlantic forest endemic species, especially those resistant to very small fragments of forest, such as D. lucida, the small putative refuges were as important as, or even more important than, larger and stable refuges for the creation and maintenance of diversity, adding another piece to the puzzle of the mechanisms underlying local endemism. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 949–960.     

Influence of pollen origin on performance of Bombus terrestris micro-colonies

The effect of the floral origin of pollen on the reproductive success of Bombus terrestris Latrum bumblebee (Apidae: Bombinae), was investigated by feeding micro-colonies of queenless workers with different pollen types. We used a commercial pollen blend and three unifloral pollens, Prunus, Salix, and Taraxacum. Among the unifloral pollens, pollen quality did not influence egg production, but did influence egg laying delay and larval growth. The quality of pollens varied according to their protein content and protein efficacy (PE). Pollen from Prunus (27.5% w/w protein, PE=10) resulted in the largest number of progeny, whereas Taraxacum (17.2% w/w protein, PE=0) did not result in any offspring, due to high oophagy and larval ejection. Salix (20% w/w protein) and the blend (22.8% protein) diets gave rise to intermediate reproductive outputs. When pollen quality was sufficient for larval growth, the fitness of the male offspring was not affected over the range of the experimental diets. Our results suggest that quantitative and qualitative variations of pollen proteins have considerable influence on the reproductive success of bumblebees. Furthermore, larval growth has specific nutritive demands not provided by Taraxacum pollen, which is missing two essential amino acids.     

Mating behaviour of Rhytidoponera sp. 12 ants inferred from microsatellite analysis

In the queenless ponerine ant Rhytidoponera sp. 12, all workers have a spermatheca and functional ovaries and are potentially able to mate and reproduce. Within a colony gamergates may either be full sisters to each other (Type 1 colony), or they may not be full sisters but still be significantly related to each other (Type 2 colony) due to daughter gamergates reproducing in their natal colonies after mating. Despite many studies the mating behaviour of R. sp. 12 has been poorly understood. In this study, we used microsatellite markers to investigate intracolony relatednesses of male mates to the gamergates (bmq) and between male mates (bmm), and mating frequencies and mating patterns, using gamergate DNA and sperm DNA isolated from the spermathecae of gamergates from five colonies. Average bmm and bmq estimates for all five colonies studied were not significantly different from zero, suggesting that on average, within colonies, mating males were unrelated both to each other and to the gamergates. A low frequency (3%) of multiple mating by gamergates was detected. Multiple mating by individual males with sister gamergates within Type 1 colonies was also detected at 3% and could give rise to half-sister nestmate workers. Polygamy in R. sp. 12 might indicate local female-biased operational sex ratios despite the expectation of overall male biases. Our results concur with previous reports that gamergates mate within the colony or nearby, but indicate more diversity in mating patterns than previously indicated for this polygynous ponerine ant species.     

地熊蜂蜂群发育性状评价及其饲料花粉配比优化

【目的】为了明确熊蜂蜂群发育过程中具有代表性的性状指标及其饲料花粉最优配比。【方法】以山杏Armeniaca sibirica花粉、山柳Salix caprea花粉和油菜Brassica rapa花粉为原料,通过{3,3}混料设计得到7种配比的混合花粉,分析不同混合花粉对地熊蜂Bombus terrestris(L.)无王工蜂群的产卵前时间、幼虫拖出数、幼虫总数量、幼虫总重量、蛹总数量、蛹总重量、雄蜂出房时间、出房雄蜂数量和雄蜂出生重9个蜂群性状指标的影响,使用主成分分析对蜂群性状指标进行综合评价,并通过混料回归模型预测熊蜂蜂群饲养过程中的最优花粉配比。【结果】地熊蜂无王工蜂群发育过程的9个性状指标可以归纳为幼虫发育、蛹发育、成蜂发育、蜂群发育周期4类评价因子,其中幼虫总数量、蛹总重量、雄蜂出生重、产卵前时间和雄蜂出房时间是5个主要性状指标;以蜂群主要性状指标为评价依据,得出蜂群饲养过程中最优花粉配比:当以油菜花粉单独饲喂蜂群时蜂群产卵前时间短、幼虫总数量最多、蛹总重量最大,当山杏花粉、山柳花粉和油菜花粉以1︰1.5︰1.5比例饲喂蜂群时雄蜂出房时间最短,当山柳花粉和油菜花粉以3︰1比例饲喂蜂群时雄蜂出生重最大。【结论】明确了地熊蜂无王工蜂群发育过程中的重要性状指标和饲料花粉最优配比,为进一步研究商品化熊蜂群不同发育阶段的营养需求奠定了基础。     

Social mutilation in the Ponerine ant <Emphasis Type="Italic">Diacamma</Emphasis>: cues originate in the victims

Summary. In the queenless ponerine ant genus Diacamma, all workers eclose with a pair of innervated thoracic appendages termed gemmae. The gamergate (= mated egg laying worker) maintains reproductive monopoly by mutilating the gemmae of all eclosing individuals. Such mutilation leads to irreversible behavioural and neurological changes such that the individual lacking gemmae becomes incapable of appropriate sexual calling and mating. In one population related to Diacamma ceylonense from India, Diacamma sp. from Nilgiri (hereafter referred to as nilgiri), gamergates do not mutilate their nestmates and yet maintain reproductive monopoly. To understand what triggers mutilation, we exchanged cocoons between the mutilating D. ceylonense colonies and the non mutilating nilgiri colonies. nilgiri callows were not mutilated even in D. ceylonense colonies while D. ceylonense callows were mutilated even in nilgiri colonies, suggesting that the cues for mutilation originate in the victims (callows), presumably in the gemmae themselves. This finding should facilitate understanding the proximate mechanism and evolutionary significance of mutilation of gemmae as a method of resolution of reproductive conflicts in the genus Diacamma.Received 27 August 2003; revised 26 April 2004; accepted 27 April 2004.     

A Novel Method of Assessing Dominance Hierarchies Shows Nuance,Linearity and Stability in the Dinosaur Ant Dinoponera quadriceps

Many social species with relatively simple societies have dominance hierarchies of individuals, with dominant individuals achieving fitness and subordinate individuals either queuing to obtain fitness or achieving only indirect fitness by helping relatives. Assessing the dominance hierarchy in a social group is generally based upon observing dyadic interactions as and when they occur spontaneously within the whole‐group setting. However, this method can be very time‐consuming because many dyads interact only very rarely, necessitating either extremely long observation periods or many dyadic relationships being unresolved. Here, we report an alternative method using the queenless dinosaur ant Dinoponera quadriceps, which lives in colonies containing tens of individuals. We removed all individuals from their nest and observed the dominance behaviours expressed in isolated dyadic interactions for every pairwise combination of individuals. Individuals showed a classic dominance behaviour in this setting, and the rapid nature of the assay allowed us to observe every dyadic relationship on a weekly basis over 4 weeks. The dominance hierarchies based on these isolated dyadic interactions correlated well with those produced by the conventional method of colony observations. They showed the hierarchies to be highly linear and stable, and also revealed that dominance relationships may extend further down the hierarchy than previously thought. Although highly manipulative, the isolated dyadic interaction method works well and will likely make more feasible the study of other social species in which pairs of individuals can be isolated together.     

Differentiation of the reproductive tract between dominant and subordinate workers in the Japanese queenless ant Diacamma sp.

In queenless ants, gamergates (mated egg‐laying workers) fulfil the reproductive task normally reserved for the queen. Every worker is a potential gamergate, thus we expect pronounced conflicts over sexual reproduction within their colonies. In the queenless ant genus Diacamma, gamergates inhibit nest mates from mating by aggressively removing (‘mutilating’) a pair of small appendages on the thorax, termed gemmae, shortly after eclosion. Dissection and serial sectioning of the reproductive tracts of both mutilated and unmutilated individuals of Diacamma sp. from Japan at different ages revealed that mutilation inhibits the development of the bursa copulatrix and the spermatheca, two structures fundamental for sexual reproduction. The precursor of the bursa copulatrix develops into a fully functional structure in unmutilated individuals, whereas it degenerates irreversibly in mutilated callows. Experimental manipulations showed that the removal of the gemmae is not the sole factor regulating this development. The spermathecal epithelium and accessory spermathecal gland of unmutilated individuals are thicker than that of mutilated individuals, indicating a higher degree of activity in the former. Mutilated females are therefore left incapable of copulating and less competent for long‐time sperm storage.