The American tropics, or the Neotropics, is a biogeographic region home of unique animal and plant species, such as anteaters, macaws, blue Morpho butterflies, passion flowers, airplants and lobster-claw plants. The rich diversity of life, or biodiversity, found in this region goes hand in hand with the variety of climates, landscapes and elevations. From central Mexico all the way to southeastern Brazil, the main Neotropical ecoregions include lowland rain forests (e.g., Amazonia), savannas (e.g., Cerrado), islands (e.g., Greater Antilles) and mountains (e.g., tropical Andes). A fair question can arise from these observations: is the unique and rich biodiversity of the Neotropics a result of environmental complexity? Indeed, we scientists have been testing this hypothesis, and other alternatives, in the light of different evidence including fossils, DNA and mathematical models. If you want to know more about the alternative hypotheses on the origin of Neotropical biodiversity, and the methods that we use to study it, jump to our EU-funded project, to our past research, or to the published scientific articles.
Neotropics in the past
Neotropical biodiversity today is the result of a long evolutionary history measured in millions of years (Myr). The past 25 Myr in particular has had a dramatic effect on the diversity of species that we see nowadays. The initial uplift of the Andes by the beginning of the Neogene geologic period (about 23 Myr ago) triggered large-scale environmental changes in ancient South America:
The Andean mountains would become a massive barrier for plant and animal dispersal between eastern (the Pacific coast of South America) and western South America (Amazonia).
The rise of the Andes would change atmospheric circulation and rainfall patterns. The Andean mountains would intercept westward-flowing tropical Atlantic moisture, which led to the humidification of Amazonia and desertification of the central Pacific coast in South America (Peru and Chile).
The Andean uplift would change the fluvial system of South America. The rising elevations of western South America led the formation of the Pebas wetland system, a network of lakes, swamps and flooded areas connecting western Amazonia and the northern coast of South America. However, the same accelerating uplift process of the Andes would terminate the Pebas wetland system by changing the course of the drainage from high mountains in the west toward the Atlantic coast in the east. By 10 Myr ago, the fluvio-tidal Acre system was established, which would later be replaced by the eastward-flowing Amazon River .
The Neogene and the Quaternary (the past 20 Myr) have thus had remarkable impacts on the evolution of Neotropical species. Events such as the major uplift of the Andes, the closure of the Isthmus of Panamá, the dynamic lacustrine-fluvial system, and the Pleistocene Ice Ages, altered the composition and distribution of organisms that we see nowadays.
The Neotropics is the most biodiverse region on Earth. The species diversity of butterflies follows this pattern with more than 7700 named and described butterflies, or roughly, the 40% of known butterflies on Earth. Butterfly experts estimate that the actual butterfly species diversity in the Neotropics can be as high as 8,700 species! Discovering the remaining thousand or so butterfly species is challenging, because we don’t know where they are or what morphological characters can be used to tell apart from sister species. Cryptic species, or species that closely resemble each other, can be discovered using multiple evidence, including DNA data. In our research, we aim to use molecular approaches to clarify butterfly taxonomy, and to understand butterfly systematics, biogeography and macroevolution.
Biogeography and species diversification of Neotropical butterflies
Our project MARIPOSAS was funded by the European Union’s Horizon 2020 research and innovation programme (Marie Skłodowska-Curie fellowship). The aim of this project was to integrate different lines of research to study evolutionary processes (speciation, extinction, dispersal) that shaped current butterfly diversity.
We studied butterflies classified in two families, Hesperiidae and Nymphalidae. Our research looked into macroevolutionary patterns of these species from different perspectives. These included: phylogenomics, macroevolutionary rates, historical biogeography and molecular species delimitation.
- Systematics and species delimitation of butterflies in the tribe Haeterini (Satyrinae). Many of these charismatic insects have transparent wings as well as bright-colored patches on the wings surface. The phylogenetic relationships within the group were not completely clear, and we aimed to provide important insights using molecular information. (Matos-Maraví et al., 2019).
- The clarification of the systematics of the tribe Brassolini (Satyrinae). This is a species rich group, consisting of more than 100 species distributed throughout the Neotropical region. We use both a large molecular alignment and morphological matrix (250 characters) to better understand the evolutionary history of the group. We aim to clarify dispersal and diversification patterns in major Neotropical biomes, such as Amazonia, Atlantic forest and Mesoamerica (Matos-Maraví et al., in preparation).
The project above has received funding from the European Union’s Horizon 2020
research and innovation programme under the Marie Skłodowska-Curie grant agreement No 704035
- Elucidation of the evolutionary history of the “Taygetis clade”. The major uplift of the Andes apparently favored the diversification of the group, as well as possible host plant shifts and dispersal from southeastern Brazil towards the Andes may have been important in butterfly biogeography (Matos-Maraví et al., 2013).
- Matos-Maraví, P., Wahlberg, N., Antonelli, A., Penz, C. M. 2019: Species limits in butterflies (Lepidoptera: Nymphalidae): Reconciling classical taxonomy with the multispecies coalescent. Systematic Entomology, in press. doi: 10.1111/syen.12352.
- Antonelli, A., Ariza, M., Albert, J., Andermann, T., Azevedo, J., Bacon, C., Faurby, S., Guedes, T., Hoorn, C., Lohmann, L. G., Matos-Maraví, P., Ritter, C. D., Sanmartín, I., Silvestro, D., Tejedor, M., ter Steege, H., Tuomisto, H., Werneck, F. P., Zizka, A., Edwards, S. V. 2018: Conceptual and empirical advances in Neotropical biodiversity research. PeerJ, 6: e5644. doi: 10.7717/peerj.5644.
- Matos-Maraví, P. 2016: Investigating the timing of origin and evolutionary processes shaping regional species diversity: Insights from simulated data and Neotropical butterfly diversification rates. Evolution, 70(7): 1638-1650. doi:10.1111/evo.12960
- Matos-Maraví, P. F., Peña, C., Willmott, K. R., Freitas, A. V. L., Wahlberg, N. 2013: Systematics and evolutionary history of butteflies in the “Taygetis clade” (Nymphalidae: Satyrinae: Euptychiina): towards a better understanding of Neotropical biogeography. Molecular Phylogenetics and Evolution 66(1): 54-68. doi:10.1016/j.ympev.2012.09.005