The evolution of antennal courtship in diplazontine parasitoid wasps (Hymenoptera,Ichneumonidae, Diplazontinae)

Background

As predicted by theory, traits associated with reproduction often evolve at a comparatively high speed. This is especially the case for courtship behaviour which plays a central role in reproductive isolation. On the other hand, courtship behavioural traits often involve morphological and behavioural adaptations in both sexes; this suggests that their evolution might be under severe constraints, for instance irreversibility of character loss. Here, we use a recently proposed method to retrieve data on a peculiar courtship behavioural trait, i.e. antennal coiling, for 56 species of diplazontine parasitoid wasps. On the basis of a well-resolved phylogeny, we reconstruct the evolutionary history of antennal coiling and associated morphological modifications to study the mode of evolution of this complex character system.

Results

Our study reveals a large variation in shape, location and ultra-structure of male-specific modifications on the antennae. As for antennal coiling, we find either single-coiling, double-coiling or the absence of coiling; each state is present in multiple genera. Using a model comparison approach, we show that the possession of antennal modifications is highly correlated with antennal coiling behaviour. Ancestral state reconstruction shows that both antennal modifications and antennal coiling are highly congruent with the molecular phylogeny, implying low levels of homoplasy and a comparatively low speed of evolution. Antennal coiling is lost on two independent occasions, and never reacquired. A zero rate of regaining antennal coiling is supported by maximum parsimony, maximum likelihood and Bayesian approaches.

Conclusions

Our study provides the first comparative evidence for a tight correlation between male-specific antennal modifications and the use of the antennae during courtship. Antennal coiling in Diplazontinae evolved at a comparatively low rate, and was never reacquired in any of the studied taxa. This suggests that the loss of antennal coiling is irreversible on the timescale examined here, and therefore that evolutionary constraints have greatly influenced the evolution of antennal courtship in this group of parasitoid wasps. Further studies are needed to ascertain whether the loss of antennal coiling is irreversible on larger timescales, and whether evolutionary constraints have influenced courtship behavioural traits in a similar way in other groups.

     

钙离子对PSII颗粒放氧活性的影响

外加5 mmol/L Ca~(2 )可以使菠菜PSⅡ颗粒的放氧活性增高。PSⅡ颗粒经EGTA透析、低pH值、光照、2 mol/L NaCl等处理后,放氧活性下降,同时,这些颗粒的钙含量也相应降低。但当外加 5 mmol/L Ca~(2 )时,可使这些颗粒全部或部分地恢复放氧活性。PSⅡ颗粒中存在的钙对放氧起着重要作用;钙在PSⅡ颗粒中的结合位点不止一个,其结合状态有紧密和松散之别。     

COMPARISON OF EUTHECOSOMATOUS PTEROPODS IN THE PLANKTON AND SEDIMENTS OFF BARBADOS, WEST INDIES

The euthecosomatous pteropod fauna of Barbados plankton wascompared with euthecosome shells occurring in recent sediments.Twenty species of euthecosomes were collected in the same relativeabundance in both provinces. Differences in the average sizesof Spiratella inflata and Creseis virgula conica, the most commonspecies were not statistically significant although differencesin the size-frequency histograms were noted. It is concludedthat euthecosomes deposited in the upper sediment layers offBarbados accurately reflect the species composition and relativeabundance of euthecosome species in the plankton. ¹Supported by a Postgraduate Scholarship from the National ResearchCouncil of Canada and NRC Grant No. A5248 to Dr. C.M. Lalli. ²Present address: Department of Oceanography, Dalhousie University,Halifax, Nova Scotia, Canada.     

Unique mid‐tract loss of a primary remex in male broadbills of the Southeast Asian genus Calyptomena: timing and possible implications

Female Calyptomena broadbills have 10 large primaries, whereas adult males have nine. At or before the main post‐juvenile moult, males abort what appears to be juvenile P5. This creation of row space is accompanied by a shortening of the wing tip, a development (together with tail shortening) that, as in some Neotropical suboscines, may relate to performance of exaggerated displays. Calyptomena has been linked taxonomically with Afrotropical Smithornis, the one genus of broadbills with proven display‐related modification of flight‐feathers.