Morphometric analysis of wild-caught flies of Drosophila (Diptera: Drosophilidae) species: Altitudinal pattern of body size traits, wing morphology and sexual dimorphism

Abstract

Literature concerning phenotypic variation among wild-caught drosophilids inhabiting varied ecological habitats is relatively rare. The present study explores pattern of body size traits along altitudinal gradients, and compensation to colder environments and reduced air pressure via adjustment of wing morphology at higher altitudes. Wild adult flies were collected in two extensive surveys during September-October 2014 and April-May 2015. All traits were measured for both the sexes to obtain data on sexual dimorphism. It was found that though these populations differed significantly in their size, as already known, they deviated from the expected reaction norms of size increase along altitudinal gradients as observed in several previous studies. This deviation from normal clinal trend can be attributed to variation in growth rates and development times at different altitudes which has important implications in overall reproductive success. Also, a significant increase in wing area of flies at higher altitude was recorded with dramatically lower wing loadings than flies that developed in comparatively warmer habitats, giving them an aerodynamic advantage at cold temperatures. Thorax width was also analyzed, possibly for the first time in wild-caught flies of Indian populations, revealing sexual dimorphism. The ratio of thorax length to width was greater than one for all species indicating that the thorax is more elongated in females, which may also influence the flight capacity of the sexes.

Keywords

• Bergmann rule,Diptera,Drosophilidae,morphometric traits,plasticity

Doğadan yakalanan Drosophila (Diptera: Drosophilidae) türlerinin morfometrik analizi: Vücut büyüklüğü özelliklerinin yüksekliğe bağlı değişimi, kanat morfolojisi ve eşeysel dimorfizmi

Öz

Çeşitli ekolojik habitatlarda yaşayan doğadan toplanmış Drosophila türleri arasındaki fenotipik çeşitlilik ile ilgili literatür sayısı nispeten azdır. Bu çalışmada vücut boyutu özelliklerinin yükseklik eğrileri boyunca olan uyumu ve daha yüksek yerlerde kanat morfolojisinin değişimiyle daha soğuk ortamlara ve daha düşük hava basıncına uyum sağlanması incelenmiştir. Doğadan ergin sinekler, Eylül-Ekim 2014 ve Nisan-Mayıs 2015 tarihlerinde iki kapsamlı sürvey ile toplanmıştır. Eşeysel dimorfizmi hakkında bilgi edinmek için her iki cinste de tüm özellikler ölçülmüştür. Bilindiği gibi, bu popülasyonların boyutlarında önemli farklılıklar olmasına rağmen, daha önceki birçok çalışmada gözlemlendiği gibi, yükseklik eğrileri boyunca boyut artışının beklenen reaksiyon normlarından sapmış oldukları bulunmuştur. Normal klinal eğimindeki bu sapma, genel üreme başarısında önemli etkileri olan farklı yüksekliklerde büyüme hızlarındaki ve gelişim zamanlarındaki farklılıklara bağlanabilir. Ayrıca, yüksek irtifadaki sineklerin kanat alanlarındaki önemli bir artış, karşılaştırmalı olarak daha sıcak habitatlarda gelişen sineklerden dramatik olarak çok daha düşük kanat yükleri ile rekor kırmış olmaları sayesinde onlara soğuk hava koşullarında aerodinamik bir avantaj sağlamıştır. Bu arada, muhtemelen Hint popülasyonlarının doğadan yakalanmış sineklerinde ilk kez, Thoraks genişliği, cinsel dimorfizmi açığa çıkararak analiz edilmiştir. Thoraks uzunluğunun genişliğe oranı tüm türler için birden fazla olup; bu da eşeylerin uçuş kapasitesini etkileyebilen thoraksın dişilerde daha uzun olduğunu göstermektedir.

Anahtar Kelimeler

• Bergmann kuralı,Diptera,Drosophilidae,morfometrik özellikler,plastisite

Kaynakça

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