Periodic Reporting for period 1 - PALAEOINVA (Palaeoecological Exploration of Human-Linked Biological Invasions on Madagascar)
Reporting period: 2023-07-01 to 2025-06-30
Loss of biodiversity – a term encompassing the variety and variability of life on earth – is one of the most urgent threats to humans and the broader biosphere. The fossil record documents a long history of where animals lived, what they ate, and when they went extinct, and understanding what influenced this record gives essential context for guiding modern conservation efforts. Biodiverse islands such as Madagascar, which are being deforested and invaded by introduced animals, are foci of biodiversity conservation efforts. People arrived on Madagascar at least 1,500 years ago and brought with them exotic predators such as dogs and rats. Though these animals are known today to threaten native animals on Madagascar by eating them, competing over resources, and spreading disease, the antiquity, past consequences, and legacy of these threats are poorly known.
This project uses novel chemical analyses of ancient animal bones to learn more about when exotic predators first arrived on Madagascar, how the diet of these predators compared with that of their native counterparts, and any adjustments that these animals likely made in response to past loss of forest and climate drying. We predicted that the history of interaction between exotic animals (specifically dogs, rats, and mice) and native animals (fosa, mouse lemurs, and rodents) extends for at least one millennium. We also expected exotic predators to have eaten a relatively broad range of foods and to have adjusted to past forest loss by increasingly eating in grasslands. Meanwhile, we expected native animals to adjust relatively well to past and ongoing climate drying by eating foods in dry areas. By testing these ideas, we will give novel insight on how vulnerable native animals are to particular stressors. This information can then contribute directly to biodiversity conservation planning, which is otherwise solely informed by direct observations of living animals.
This project uses novel chemical analyses of ancient animal bones to learn more about when exotic predators first arrived on Madagascar, how the diet of these predators compared with that of their native counterparts, and any adjustments that these animals likely made in response to past loss of forest and climate drying. We predicted that the history of interaction between exotic animals (specifically dogs, rats, and mice) and native animals (fosa, mouse lemurs, and rodents) extends for at least one millennium. We also expected exotic predators to have eaten a relatively broad range of foods and to have adjusted to past forest loss by increasingly eating in grasslands. Meanwhile, we expected native animals to adjust relatively well to past and ongoing climate drying by eating foods in dry areas. By testing these ideas, we will give novel insight on how vulnerable native animals are to particular stressors. This information can then contribute directly to biodiversity conservation planning, which is otherwise solely informed by direct observations of living animals.
The work initially planned for two years is still in progress given an early termination of the Marie Curie fellowship (6 months after starting) and the transition of the postdoctoral fellow to support from the National Science Foundation in the USA. The Marie Curie fellowship was a success, because it provided essential support at the early stages of the project and accelerated the fellow’s academic career through the collaborations formed in the process. During the months of fellowship tenure, we already made significant progress with compiling relevant datasets (WP4), inventorying and sampling bone collections (WP1), developing lab protocols (WP1, 3, & 5), and extracting and purifying organics from ancient bone (WP1).
Existing sedimentary archives and chemical data from modern plant and animal tissues give valuable context for interpreting the data that we are generating through this project. We have compiled all existing stable isotope data from samples previously collected from the animals that we are studying on Madagascar. We have also compiled all chronological data associated with previously published sedimentary archives so that we can easily link our ancient animal records with ancient records of deforestation and climate drying while accounting for chronological uncertainty.
The ancient animal bone that we are using for this study comes primarily from a recently excavated site in SW Madagascar called Andaboy. We have been inventorying this collection, which includes over 8,000 identified specimens. To better estimate when exotic animals arrived on the island, we have worked to expand sample sizes from other ancient bone deposits that were previously recovered across the island. This has included sampling 127 bones at the University of Antananarivo’s paleontology collection and submitting requests for sampling collections housed at the Natural History Museum in London and the National Museum of Natural History in Paris.
We have also worked to increase the efficiency of extracting ancient bone organics and to improve our ability to purify protein residues from small and poorly preserved samples through resin column chromatography. The new protocols were effectively tested and have since been successfully applied to ancient small mammal bones that started with as little as 14 mg of material. We also made progress in establishing protocols for treating samples prior to amino acid specific stable isotope work.
Extraction and purification of ancient bone organics is complete for some groups. In addition to the 20 dogs and 15 fosa with existing data mentioned in the proposal, we have purified ancient bone organics from another 7 dogs and 23 fosa. We have also prepared residues from 14 native small mammals (mostly shrew tenrecs), 13 mouse lemurs, 18 introduced shrews, 26 introduced mice, and 52 introduced rats. Mouse lemurs sampled outside of our main site of Andaboy tend to be too poorly preserved to permit analysis. However, aside from introduced shrews, additional samples are available to prepare from all small mammal groups. We are awaiting stable isotope and radiocarbon results from the first batch of samples before continuing to work with sample extraction and amino acid specific stable isotope analysis.
Existing sedimentary archives and chemical data from modern plant and animal tissues give valuable context for interpreting the data that we are generating through this project. We have compiled all existing stable isotope data from samples previously collected from the animals that we are studying on Madagascar. We have also compiled all chronological data associated with previously published sedimentary archives so that we can easily link our ancient animal records with ancient records of deforestation and climate drying while accounting for chronological uncertainty.
The ancient animal bone that we are using for this study comes primarily from a recently excavated site in SW Madagascar called Andaboy. We have been inventorying this collection, which includes over 8,000 identified specimens. To better estimate when exotic animals arrived on the island, we have worked to expand sample sizes from other ancient bone deposits that were previously recovered across the island. This has included sampling 127 bones at the University of Antananarivo’s paleontology collection and submitting requests for sampling collections housed at the Natural History Museum in London and the National Museum of Natural History in Paris.
We have also worked to increase the efficiency of extracting ancient bone organics and to improve our ability to purify protein residues from small and poorly preserved samples through resin column chromatography. The new protocols were effectively tested and have since been successfully applied to ancient small mammal bones that started with as little as 14 mg of material. We also made progress in establishing protocols for treating samples prior to amino acid specific stable isotope work.
Extraction and purification of ancient bone organics is complete for some groups. In addition to the 20 dogs and 15 fosa with existing data mentioned in the proposal, we have purified ancient bone organics from another 7 dogs and 23 fosa. We have also prepared residues from 14 native small mammals (mostly shrew tenrecs), 13 mouse lemurs, 18 introduced shrews, 26 introduced mice, and 52 introduced rats. Mouse lemurs sampled outside of our main site of Andaboy tend to be too poorly preserved to permit analysis. However, aside from introduced shrews, additional samples are available to prepare from all small mammal groups. We are awaiting stable isotope and radiocarbon results from the first batch of samples before continuing to work with sample extraction and amino acid specific stable isotope analysis.
The results and associated policy relevance are not yet available given the early termination of the fellowship. However, the research is ongoing, and we will continue to acknowledge the support of the Marie Curie Fellowship in all outreach and publications given the key support in getting the project started.