Age, but Not Experience, Affects Courtship Gene Expression in Male Drosophila melanogaster

Mutation screens in model organisms have helped identify the foundation of many fundamental organismal phenotypes. An emerging question in evolutionary and behavioral biology is the extent to which these “developmental” genes contribute to the subtle individual variation that characterizes natural populations. A related question is whether individual differences arise from static differences in gene expression that arose during previous life stages, or whether they are due to dynamic regulation of expression during the life stage under investigation. Here, we address these questions using genes that have been discovered to control the development of normal courtship behavior in male Drosophila melanogaster. We examined whether these genes have static or dynamic expression in the heads of adult male flies of different ages and with different levels of social experience. We found that 16 genes of the 25 genes examined were statically expressed, and 9 genes were dynamically expressed with changes related to adult age. No genes exhibited rapid dynamic expression changes due to social experience or age*experience interaction. We therefore conclude that a majority of fly “courtship” genes are statically expressed, while a minority are regulated in adults with respect to age, but not with respect to relevant social experience. These results are consistent with those from a recent microarray analysis that found none of the canonical courtship genes changed expression in male flies after brief exposure to females

Photography-based taxonomy is inadequate, unnecessary, and potentially harmful for biological sciences

The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & Nemésio 2007; Donegan 2008, 2009; Nemésio 2009a–b; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per the editorial rules of Nature) was submitted to Nature, which on 18 October 2016 refused to publish it. As we think this problem is a very important one for zoological taxonomy, this text is published here exactly as submitted to Nature, followed by the list of the 493 taxonomists and collection-based researchers who signed it in the short time span from 20 September to 6 October 2016

Linear discriminant loading scores.

<p>Linear discriminant loading scores.</p

Analysis of variance on individual genes.

1<p>Astericks represent significance after FDR correction for multiple hypothesis testing.</p><p>^*p<0.05, ^**p<0.01, ^***p<0.001.</p

Expression levels of individual genes for each age/experience category.

<p>Relative expression levels standardized to “IN” category are reported, as well as corresponding standard errors. Only genes with significant differences in expression due to age are displayed.</p

qRT-PCR primers.

<p>qRT-PCR primers.</p

Description of courtship foundation (CF) genes, including putative molecular and behavioral function.

*<p>Calcium/calmodulin-dependent protein kinase II.</p>†<p>no on or off transient A.</p

Gene expression profiles of age and experience categories.

<p>Single factor hierarchical clustering of expression profiles; red indicates increased expression, blue indicates decreased expression (as compared to the mean standardized expression taken over all genes and treatments). Three distinct clusters were found, and are identified by the color bars on the right. These clusters are discussed in the text. Full gene names are listed in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0006150#pone-0006150-t001" target="_blank">Table 1</a>.</p

Plot of linear discriminant (LD) scores.

<p>“IN”: immature and naïve; “IE”: immature having encountered a female; “MN”: mature and naïve; “ME”: mature with courtship experience. A) LD1 vs. LD2. B) LD1 vs. LD3.</p