Summary 1.A central tenet of life-history theory is that investment in reproduction compromises survival. However, the underlying physiological mechanisms that link reproduction to survival are poorly understood, particularly in wild populations. 2. Previous experiments in the brown anole lizard (Anolis sagrei) show that the elimination of reproduction via surgical ovariectomy results in a dramatic increase in the survival of wild females. We hypothesized that this trade-off reflects underlying differences in energy allocation between reproduction and physiological processes that influence survival. 3. To test this hypothesis, we compared ovariectomized (OVX) females to reproductive controls (SHAM) with respect to four physiological parameters that are thought to influence survival: energy storage, haematocrit, immune function and parasitemia. 4. Consistent with previous studies, we found that OVX females exhibited increased survival and growth relative to reproductive SHAM females. At the end of the breeding season, OVX also exceeded SHAM with respect to energy storage, haematocrit and immune response to phytohemagglutinin challenge. 5. Contrary to our predictions, OVX were more likely than SHAM to exhibit high levels of parasitemia. However, growth and parasite load were positively correlated in OVX and negatively correlated in SHAM, suggesting that reproductive investment may compromise parasite tolerance rather than parasite resistance. 6. Collectively, our results provide direct experimental evidence that reproductive investment affects several key physiological traits that likely interact to influence survival in wild populations.

Ecological Epigenetics studies the relationship between epigenetic variation and ecologically relevant phenotypic variation. As molecular epigenetic mechanisms often control gene expression, even across generations, they may impact many evolutionary processes. Multiple molecular epigenetic mechanisms exist, but methylation of DNA so far has dominated the Ecological Epigenetic literature. There are several molecular techniques used to screen methylation of DNA; here, we focus on the most common technique, methylation-sensitive-AFLP (MS-AFLP), which is used to identify genome-wide methylation patterns. We review studies that used MS-AFLP to address ecological questions, that describe which taxa have been investigated, and that identify general trends in the field. We then discuss, noting the general themes, four studies across taxa that demonstrate characteristics that increase the inferences that can be made from MS-AFLP data; we suggest that future MS-AFLP studies should incorporate these methods and techniques. We then review the short-comings of MS-AFLP and suggest alternative techniques that might address some of these limitations. Finally, we make specific suggestions for future research on MS-AFLP and identify questions that are most compelling and tractable in the short term.

The spread of invasive species presents a genetic paradox: how do individuals overcome the genetic barriers associated with introductions (e.g., bottlenecks and founder effects) to become adapted to the new environment? In addition to genetic diversity, epigenetic variation also contributes to phenotypic variation and could influence the spread of an introduced species in novel environments. This may occur through two different (non-mutually exclusive) mechanisms. Individuals may benefit from existing (and heritable) epigenetic diversity or de novo epigenetic marks may increase in response to the new environment; both mechanisms might increase flexibility in new environments. Although epigenetic changes in invasive plants have been described, no data yet exist on the epigenetic changes throughout a range expansion of a vertebrate. Here, we used methylation sensitive-amplified fragment length polymorphism to explore genome-wide patterns of methylation in an expanding population of house sparrows (Passer domesticus). House sparrows were introduced to Kenya in the 1950s and have significant phenotypic variation dependent on the time since colonization. We found that Kenyan house sparrows had high levels of variation in methylation across the genome. Interestingly, there was a significant, potentially compensatory relationship between epigenetic and genetic diversity: epigenetic diversity was negatively correlated with genetic diversity and positively correlated with inbreeding across the range expansion. Thus, methylation may increase phenotypic variation and/or plasticity in response to new environments and therefore be an important source of inter-individual variation for adaptation in these environments, particularly over the short timescales over which invasions occur.

Summary 1.Ecologists are becoming increasingly interested in characterizing immunological variation among and within species. However, many of the techniques available to immunologists are not viable for use in non-model species, which limits the resolution and progress of ecoimmunological research. Recently, an assay was developed to quantify the capacity of blood or plasma to kill microorganisms in vitro. Such assays are ideal for ecologists because they provide holistic, integrated measures of immune function with minimal sample size and equipment. 2. Although informative, the assay suffers from several shortcomings in its current form. Specifically, intra-assay variation is often prohibitive, quantification of results is time consuming, sample volumes required are somewhat high (especially for small-bodied species), and materials (e.g. Petri dishes for microbe culturing) are costly and generate excessive waste. 3. Here, we describe a modified version of the assay for use against Gram-negative, Gram-positive, and fungal microbes using spectrophotometry. This assay decreases sample processing time, reduces blood ⁄ plasma volume (to 1AE5 lL), and eliminates the need to score results manually. This technique was 3· more reliable than the alternative method when using house sparrow Passer domesticus plasma and Escherichia coli. 4. We expect this assay will enable quantification of immune defence in a variety of contexts previously difficult to study (e.g. endangered species) because of the small volumes needed and the simplicity of the protocol. We also provide a list of pathogens that affect passerine populations as potential candidates in future studies. Anti-microbial activity in other animal species should also be easy to characterize using our approach and the quantification of antimicrobial capacity of tissue and other body fluids should also be possible with only minor modifications of the assay.