In the second paper to be published from Hanja’s thesis, we have demonstrated that zebra finches would rather nest next to a pair that are also just starting to breed, than a pair that is further along. Hanja and team demonstrated this by erecting new empty nest boxes near to occupied boxes, at either nest-building, incubating or chick rearing stages. Pairs were far more likely to lay eggs in the experimental boxes that were close to those that had also initially been at the nest building stage. We believe that these results are driven by the social benefits of breeding alongside other pairs at a similar stage of activity. The paper is published in the journal Animal Behaviour, and can be downloaded for free in the next month using this link.
A paper by student Victoria Austin, completed while she was an MRes student in the lab has just been published, focused on the almost incessant singing of the chirruping wedgebill – a song that will be familiar to anyone who has worked at Fowlers Gap, or elsewhere in the range of this arid zone bird. The paper, entitled ‘Song rate and duetting in the Chirruping Wedgebill (Psophodes.cristatus): frequency, form and functions’ has been published in Emu – Austral Ornithology. The paper can be found here.
Even though it was extremely dry at Fowlers Gap this spring, our zebra finch field season was a successful one. Luckily for us, zebra finches were still present in large numbers despite the drought. Interestingly, zebra finches were still found singing actively although hardly any breeding attempts were made.
In a new collaborative project with Marc Naguib and Hugo Loning of Wageningen University, the Netherlands, we will look into more detail at wild zebra finches’ communication, especially singing behaviour. From lab studies we know that their song functions in mate choice when reaching maturity, but why they sing for the rest of their adult life remains unclear.
To this end we have installed a large number of passive acoustic monitoring devices which enables us to monitor the acoustic environment during and outside of breeding seasons, in a variety of habitats for years to come. This will not only contribute to zebra finches studies, but also gives us valuable information on the presence of other birds, which will benefit additional studies on bird ecology, migration and conservation in these unpredictable, extreme environments.
Our paper on genetic changes in response to Lead pollution in the outback towns of Broken Hill (NSW) and Mount Isa (Queensland), has been published in the journal, Science of the Total Environment. The paper, “Signs of adaptation to trace metal contamination in a common urban bird” focuses on changes in the frequency of 35 SNP’s linked to a number of genes, some of which have been shown to relate to the transfer of heavy metals across cell membranes.
The study, led by Sam Andrew, and part of his PhD project was done in collaboration with the team in Trondheim led by Henrik Jensen, and also Mark Taylor at MQ.
In September we conducted fieldwork on either side of the NT and WA border to sample long-tailed finches in the area where the eastern and western forms of the Z chromosome meet in the wild (see recent paper by Hooper et al (2018). The fieldwork team comprised Daniel Hooper and Emma Grieg (both from Cornell University), Kyle Kostrzewa, and Callum McDiarmid and Simon Griffith (Macquarie). The trip was successful and we had two weeks of camping, driving (a lot) and finding water holes and sampling birds in the area from Keep Rive in the east, to Home Valley station in the West.
Key papers for an understanding of the replication crisis in ecology and evolution and a pathway to change
Forstmeier et al (2017) Detecting and avoiding likely false-positive findings – a practical guide. Biol. Rev. 92, 1941–1968 https://DOI:10.1177/0956797611417632
Fraser et al (2018) Questionable research practices in ecology and evolution PLOS ONE https://doi.org/10.1371/journal.pone.0200303
Ihle et al (2017) Striving for transparent and credible research: practical guidelines for behavioral ecologists.Behavioral Ecology (2017), 28(2), 348–354. https://doi:10.1093/beheco/arx003
Nelson et al (2018) Psychology’s Renaissance. Annu. Rev. Psychol. 2018. 69:511–34. https://doi.org/10.1146/annurev-psych-122216-011836
Parker et al (2018) Empowering peer reviewers with a checklist to improve transparency. Nature Ecol & Evol. 2, 929–935 https://doi.org/10.1038/s41559-018-0545-z
Parker et al (2016) Transparency in Ecology and Evolution: Real Problems, Real Solutions. TREE 31, 711 http://dx.doi.org/10.1016/j.tree.2016.07.002
Simmons et al (2011) False-Positive Psychology: Undisclosed Flexibility in Data Collection and Analysis Allows Presenting Anything as Significant. Psychological Science 22 1359–1366 https://DOI:10.1177/0956797611417632
Wang et al (2018) Irreproducible text-book “knowledge”: The effects of color bands on zebra finch fitness. Evolution https://doi:10.1111/evo.13459
Babbler and zebra finch fieldwork is underway at Fowlers Gap again in what is shaping up to be the worst drought since our work began out there in 2004. The long-term average amount of annual rainfall at Fowlers is 235mm. Since September 2016, there has been a total of 181mm across 23 months. In 2017 there was a total of just 77mm which makes it the second driest year from the 60 years for which data is available (Data from Bureau of Meteorology). So far, 2018 is looking even worse, with less than 3mm of rain recorded in the first seven months of the year.
As illustrated above, the environment is already looking extremely dry and the heat is just starting to pick up in the late winter, which will further dry the environment and challenge the animals and plants at the research station. Not surprisingly, in the work to date, there is no evidence that any of the birds are starting to breed, and the whole landscape is in urgent need of a drink.
Our recent work investigating the effects of the southern hemisphere climatic oscillations La Niña and El Niño on the timing of breeding by 64 temperate breeding species, and 15 species breeding in the arid zone. As illustrated below, La Niña is characterised by milder wet conditions in the main avian breeding period, and in such years, egg laying periods were typically longer for most species. There was a lot of variation in the response of different species and partly this was related to whether they breed early in spring. We found no obvious adverse effect of dry La Niña conditions, contrary to a prior expectation.
This study represents the most intensive examination of the effect of the southern climatic oscillation on breeding phenology in Australian birds and is focused on over 80,000 breeding records collected by a wide variety of sources over the past century.
The full paper can be found here.
Sam’s paper characterising the structure of the house sparrow populations across Australia and New Zealand, was recently published in Biological Invasions.
The main conclusion of this work is that the population genetic structure of the house sparrows across Australia and New Zealand today, largely reflects the historical introductions of these populations, that were founded by deliberate introductions in the 1850-60s, by the Acclimatization Societies that were active in New Zealand, and multiple cities across Australia. As well as confirming the historical records concerning the site of independent introductions, the strong structure that we have characterised suggests limited movement between many populations. This is interesting because it provides the opportunity for selection to act on contemporary populations fairly independently and local adaptation may result, particularly given the range of climates and ecological variation faced by the different populations.
Andrew SC, Awasthy M, Bolton PE, Rollins LA, Nakagawa S, Griffith SC, (2018) The genetic structure of the introduced house sparrow populations in Australia and New Zealand is consistent with historical descriptions of multiple introductions to each country. Biological Invasions, 6, 1507-1522.
In our most recent paper, published today in Royal Society Open Science (see article here), we examine the extent to which DNA methylation is related to genetic variation across different populations in the three introduction clusters of the house sparrow in Australia. We found no support for the idea that epigenetic variation might compensate for a lack of genetic diversity in introduced populations. However, we did find that patterns of epigenetic variation are highly variable across populations within each of these clusters, rather than having shared similarity across clusters (as in genetic variation). This study is still one of relatively few that has examined the patterns of epigenetic variation across a number of populations and contributes to our growing understanding of the role of epigenetic variation in ecology and evolution.
It is particularly timely that the study is published today, the last day at Macquarie for both Ellie Sheldon who is departing to work on a field project in the Kimberley region, and Sam Andrew, who is heading to Finland to work with Craig Primmer on his Endeavour Fellowship.
Daisy’s second published paper from her PhD research is published today in Scientific Reports and is Open Access and can be downloaded here.
The media release for this story is below and explains the main findings and their implications.
New scientific study examines why eggs are shaped as they are
- The shape of a species’ egg is determined by the climate in which they typically breed, and the extent to which their nest protects the egg from the sun.
- The classically-shaped eggs with which we are so familiar have a greater surface area to volume ratio than a spherical egg, allowing for a greater level of gas exchange between the embryo and the environment.
- As Easter approaches and the shops are full of chocolate eggs, it is a good time to be wondering why bird eggs are egg shaped and not nice round balls.
A new study published today in Scientific Reports by scientists from Macquarie University helps us understand why the classic egg shape evolved in birds and explains some of the species variation in egg shape.
The study examined egg shape in over 300 species of Australian birds, that live across some of the most extreme climates on earth, from the wet and humid tropics, to the dry and hot inland deserts.
The study found that the shape of a species’ egg is determined by the climate in which they typically breed, and the extent to which their nest protects the egg from the sun.
The most spherical eggs were typically found in desert species nesting in open nests, where the embryo inside the egg is likely to be damaged by the heat from the sun and dehydration. The most elongated or ‘egg-shaped’ eggs were found in moist environments, or in species that have enclosed nests, which are not exposed to the elements.
Lead author Daisy Duursma from the Department of Biological Sciences said as Easter approaches and the shops are full of chocolate eggs, it is a good time to be wondering why bird eggs are egg shaped and not nice round balls.
“There is a tension between allowing oxygen to get inside the egg so the embryo can breathe, but at the same time not allow too much moisture to escape and risk dehydration”.
The classically-shaped eggs with which we are so familiar have a greater surface area to volume ratio than a spherical egg, allowing for a greater level of gas exchange between the embryo and the environment.
The classic egg-shaped eggs are laid in relatively protected environments and prioritise gas exchange for the developing embryo to breathe, in a context where dehydration is less of a concern. The opposite is true in harsh environments where eggs are exposed to the elements.
“The egg shape is an adaptation that balances the need for the embryo to breathe without losing too much water, and can be nicely seen by looking at the eggs that are laid by different species across the diverse continent of Australia,” concluded Professor Simon Griffith, the leader of the project.
Well done to Ondi Crino (now at Deakin University), who today saw her paper published, focused on probably the most remote field sites that we’ve worked on to date. Ondi measured the condition of birds across these five different sites, which all faced different ecological conditions, likely due to the different rainfall that they had experienced over the couple of years prior to the sampling. Birds in the different locations were in different condition and their stress hormones reflected this. Both things were correlated with the amount of breeding activity that we found across these five populations. The study is a step towards understanding the mechanisms underlying the opportunistic breeding that is seen in so many Australian birds – where birds will only breed when the local conditions are good. The paper was published today in General and Comparative Endocrinology and can be found here.