Seminario de Fronteras "The Origin and Evolution of Neotropical Biodiversity"
Introduction to Professor Lucía Loman
Welcoming Remarks
- The speaker welcomes members of the biology institute and attendees, expressing great pleasure in introducing Professor Lucía Loman.
- Professor Loman has been a faculty member at the Department of Botany, Institute of Biosciences, University of São Paulo since 2004.
- She completed her undergraduate studies at the University of São Paulo and earned her master's and PhD in Ecology, Evolution, and Systematics from the University of Missouri-St. Louis.
Academic Contributions
- Professor Loman is recognized for her integrative systematic taxonomy work, focusing on Bignoniaceae (e.g., Jacarandas), as well as phylogenetics, biogeography, conservation, and Neotropical biota origins.
- Her extensive curriculum includes multiple honors from various botanical societies for outstanding contributions to botany.
Recognition and Achievements
Honors Received
- Recognized by the Brazilian Botanical Society and the Botanical Society of America for her significant contributions to botany.
- Described over 200 species and combinations; named an honorary international member by the American Academy of Sciences.
New Species Named After Her
- A new species named Distictella lomani was described in 2009 in honor of Professor Loman; it belongs to Bignoniaceae found in Brazil's Duque Reserve.
Professional Affiliations
Scientific Committees
- Active member of numerous scientific committees including the American Society of Plant Taxonomists and International Association of Plant Taxonomists.
- Editorial roles include serving on boards for journals like Resilience Journal of Botany and others; she has authored or co-authored over 150 peer-reviewed articles.
Contributions to Conferences
Conference Participation
- Keynote speaker at many international meetings including the 50th anniversary celebration for the Association for Tropical Biology.
- Played a significant role in organizing scientific conferences such as annual meetings for tropical conservation associations.
Mentorship Role
Training Future Scientists
- Supervised nine postdoctoral researchers, sixteen doctoral students, eight master's students, and ten undergraduate students.
Presentation Topic: Origin and Evolution of Neotropical Biodiversity
Introduction to Presentation
- Professor Loman expresses gratitude towards colleagues who invited her to share research projects.
- She shares excitement about discussing Neotropical biodiversity origins due to its significance among scientists globally.
Importance of Neotropical Region
Understanding Neotropical Biodiversity
Complexity of Neotropical Ecosystems
- The complexity of the neotropical biodiversity system requires integrative and multidisciplinary studies, incorporating various fields of knowledge.
- Understanding this biodiversity involves not only ecological drivers but also historical factors that have shaped it over time.
Gaps in Knowledge
- Despite significant conceptual and empirical advancements in understanding neotropical biodiversity, there remain substantial gaps in our knowledge. This indicates that we are just beginning to explore this complex system.
- A 2019 study revealed that only 17% of the known 350,000 angiosperm species have sufficient geographic, genetic, and morphological data available for analysis. This highlights the need for better data collection across different taxonomic groups.
Research Approaches
- The laboratory conducts studies on two scales: detailed investigations on specific plant groups (e.g., Bignoniaceae) and broader analyses integrating data from various plants and animals to understand evolutionary patterns in the region.
- The Bignoniaceae family includes around 850 species across 80 genera, showcasing significant morphological and ecological diversity found in both dry and wet climates. These plants play a crucial role in tropical forests due to their beauty and ecological functions.
Focus on Bignoniaceae Family
- Initial research focused primarily on trees within the Bignoniaceae family; however, many gaps existed regarding lianas (woody vines), prompting further investigation into this group which constitutes nearly half of the family's species.
- Lianas contribute significantly to forest structure and ecosystem functioning, representing up to 40% of biomass and biodiversity in tropical forests. Their importance underscores the need for comprehensive studies within this group.
Systematic Studies Objectives
- Research objectives include documenting species diversity, reconstructing phylogenetic relationships among species, and producing comprehensive taxonomic treatments for identification purposes within the Bignoniaceae family.
- Fieldwork is essential for these studies; recent expeditions to previously unexplored regions (e.g., northern Brazil near Venezuela) yielded new plant records and species discoveries vital for systematic research efforts.
Phylogenetic Studies in Bignoniaceae
Importance of Molecular Data
- The speaker discusses a phylogenetic tree developed during their doctoral thesis, which was crucial for identifying monophyletic genera for further taxonomic studies by various researchers.
- Students at different academic levels in the speaker's lab selected specific genera to conduct taxonomic reviews and reconstruct comprehensive molecular phylogenies.
Evolutionary Methods and Advances
- The evolution of sequencing methods over the past two decades is highlighted, noting an increase from using 2-3 molecular markers to whole genome sequencing with extensive base pairs.
- Initial studies utilized only a few thousand base pairs, while recent approaches involve datasets with over a million base pairs per species, leading to more robust phylogenetic trees.
Research Objectives
- The research focuses on three main objectives: studying morphological evolution patterns, testing hypotheses about adaptive value of morphological traits, and exploring genetic bases of development within the Bignoniaceae family.
Climbing Habit and Wood Anatomy
- The study emphasizes the evolution of climbing habits and ecological interactions, particularly focusing on wood anatomy diversity in Bignoniaceae.
- A detailed examination reveals that all species initially develop continuous phloem rings that later become discontinuous, leading to distinct phloem structures across species.
Evolutionary Successes in Wood Anatomy
- Unique anatomical features have evolved infrequently over 50 million years within the tribe Bignoniaceae, showcasing evolutionary success through stability in these traits.
Phloem Characteristics
- Regular phloem contains higher amounts of parenchyma compared to variant phloem; this difference contributes to storage capacity variations between types.
- Variant phloem has wider sieve tube elements and greater fiber concentrations, enhancing conduction efficiency—important for invasive species like Dolichandra.
Extra-floral Nectaries and Ecological Interactions
- Another focus is on extra-floral nectaries found on leaves and branches; these glandular structures are actually trichomes with variable morphologies.
Ant Interaction Studies
- Research indicates a strong correlation between extra-floral nectary abundance and ant visitation rates; more abundant nectaries attract more ants, suggesting protective roles for plants.
Environmental Influence on Nectary Abundance
Ecological and Evolutionary Importance of Nectaries
Role of Nectaries in Different Environments
- The study suggests that nectaries are more crucial for plant protection in humid environments compared to dry ones, indicating an evolutionary adaptation.
- Despite their low abundance in dry areas, nectaries persist, hinting at a phylogenetic inertia that maintains their presence even when they may not provide protective benefits.
Research Focus on Anemopegma Album
- The research aimed to understand why nectaries remain present in dry environments despite lacking protective functions for plants.
- Anemopegma album, a bignoniaceae species prevalent in eastern Brazil, was chosen due to its significant variation in nectary abundance across populations.
Findings on Nectary Abundance and Herbivory
- Seven out of ten studied populations exhibited low nectary concentrations (average of 12 per leaf), leading to high herbivory rates due to weak ant protection.
- Conversely, three populations showed high nectary abundance (average of 76 per leaf), resulting in strong ant visitation and lower herbivory rates.
Implications for Geographic Mosaic Theory
- The findings align with John Thompson's geographic mosaic theory of evolution, which posits that different animal assemblages can lead to varying selection pressures within the same species across different locations.
Methodology and Broader Insights
- The studies began with anatomical investigations characterizing nectary morphology, followed by functional studies documenting their protective roles against herbivores.
- This approach allowed researchers to explore how different ant and herbivore assemblages influence ecological and evolutionary pressures on nectar production.
Evolution of Pollination Systems in Bignonia
Floral Morphology Variability
- Bignonia flowers exhibit diverse colors and morphologies; external floral whorls show phylogenetic conservation while internal structures display high homoplasy.
Reproductive Isolation Mechanisms
- Variability in stamen and ovary lengths among closely related species likely contributes to reproductive isolation mechanisms within this group.
Understanding Evolutionary Forces
- These studies enhance understanding of the driving mechanisms behind morphological evolution within neotropical flora, linking them to ecological forces shaping community assembly.
Biogeographical Patterns in Bignonia Communities
Objectives of Biogeographical Study
- The biogeographical component aims to analyze community assembly over time, spatial diversity patterns, and reconstruct the historical biogeography of bignonia.
The Role of Environment in Bignonia Community Assembly
Environmental Influence on Species Distribution
- The study found that neither phylogeny nor floral morphology significantly affected the assembly of Bignonia communities; instead, habitat specialization was crucial for determining species distribution patterns.
- Bignonia originated in eastern South America approximately 50 million years ago and later spread to western South America, coinciding with the proto-Amazon region's development.
Biogeographical History of Bignonia
- The group reached Brazil's central dry diagonal around 30 million years ago, where significant diversification occurred.
- Recent studies by Laura Alagomarcino and Laura Frost have been pivotal in reconstructing the complex origins and evolution of Neotropical biodiversity.
Understanding Neotropical Biodiversity
Importance of Multi-organism Studies
- To fully grasp Neotropical biodiversity history, it is insufficient to conduct detailed studies on a single plant group; broader research involving multiple organisms is necessary.
Amazonian Biota Project Overview
- The speaker presents findings from a collaborative project on the origin and evolution of Amazonian biota, involving researchers from fifteen institutions across four countries.
- The project aimed to answer four key questions regarding the age of Amazonian biota, including fossil ages and factors contributing to diversification.
Key Questions Addressed in Research
Age Determination of Amazonian Biota
- The first question focused on determining the age of Amazonian biota through large-scale phylogenetic reconstructions across various organisms: birds, butterflies, monkeys, and plants.
Findings on Avian Diversification
- Birds originated in South America and dispersed widely through proto-Amazonia during the Late Cretaceous; however, their major diversification began post-dinosaur extinction around 65.5 million years ago.
Insights into Plant Evolution
Butterfly and Plant Phylogenetics
- Similar patterns were observed in Amazonian butterflies with origins traced back to the Late Cretaceous but significant diversification occurring after dinosaur extinction.
- Phylogenetic data indicate many angiosperm lineages date back to the Paleocene, suggesting that modern tropical forests' composition has deep historical roots.
Implications for Tropical Forest Composition
- A notable increase in angiosperm families occurred after dinosaur extinction; this suggests that South America was likely covered by tropical forests since at least the Paleocene.
Formation Age of Amazonia
Understanding Amazonia's Development
- To determine when modern-day Amazonia formed, researchers needed to assess when the dry diagonal emerged that split continuous forest cover into two main regions: Amazonia and Atlantic Forest.
Divergence Evidence Around Diagonal Formation
The Formation of the Dry Diagonal in South America
Historical Context and Geological Changes
- The establishment of the dry diagonal is suggested to have begun in the Oligocene, coinciding with cooler temperatures due to the formation of a belt between the Antarctic polar region approximately 30 million years ago.
- The rise of the Andes and Sierra de Mantiquera contributed to a drier interior continent by blocking previously moist oceanic currents that affected the region.
- Evidence indicates that while the dry diagonal began forming around 30 million years ago, various biomes within it developed later; for instance, geological data shows that Chaco formed about 23 million years ago.
Development of Biomes
- Chaco, a biome characterized by floodable vegetation, was subsequently covered by marine incursions during the mid-Miocene.
- Phylogenetic studies suggest that Cerrado, one of the richest savannas globally, originated in the mid-Miocene around 10 million years ago.
- The Caatinga biome likely emerged in the late Miocene approximately 7.5 million years ago, indicating it may be the youngest biome within the dry diagonal.
Biodiversity and Its Age
- South America was likely covered by tropical rainforests since the Paleocene; these forests became more diverse during the Eocene but fragmented with dry diagonal formation in Oligocene.
- Research aimed at understanding Amazonian biodiversity led to reconstructing phylogenies at species level across various Amazonian genera.
Divergence Patterns Among Species
- Analysis revealed divergences among Amazonian plant species dating back to as early as late Miocene; many divergences occurred during Pliocene.
- For butterflies, most divergences among sister species happened during Pleistocene; similar patterns were observed in birds and monkeys over recent millions of years.
Drivers of Diversification
- Most divergences among sister species in Amazonia occurred during Pliocene coinciding with river drainage formations.
- A hypothesis proposed by Wallace (1854), suggesting large rivers like Amazonas act as barriers reducing gene flow between populations on opposite banks leading to allopatric speciation.
Genetic Studies on River Barriers
- Genetic studies conducted on various plant populations showed high gene flow across younger rivers like Río Blanco but not across older wider rivers like Río Negro.
- Findings indicate that larger ancient rivers effectively represent barriers for gene flow while narrower newer rivers do not impede genetic exchange significantly.
Summary Insights
- The Amazonian biota has ancient roots tracing back to Late Cretaceous with diversification rates increasing post-dinosaur extinction; however, modern species are relatively young from Pleistocene era.
Research Collaboration and Findings in Amazonian Biodiversity
Acknowledgments and Introduction
- The speaker emphasizes the collaborative nature of their research, thanking various team members from different laboratories involved in the Amazon project.
- Special recognition is given to a prolific collector of Bignoniaceae, whose collections have been crucial for their work.
Q&A Session Highlights
Gene Expression and Phylogenetic Analysis
- Ivonne Garzón asks about the genes used to measure rates of return related to flower expression; the response involves using a phylogenetic tree based on two chloroplast genes and one nuclear gene.
- The speaker confirms that they found compatibility between phylogenies derived from nuclear data and those inferred from other datasets, indicating robust results.
Pollinator Diversity
- María Fernanda Martínez inquires about pollinator diversity among liana species; the speaker lists various pollinators including bees, bats, butterflies, and hummingbirds.
Plant Characteristics for Habitat Colonization
- Natalia Quinteros questions whether specific plant traits facilitated colonization of new habitats; key findings include morphological changes in seed shapes adapted for different environments.
Fossil Records and Biogeographical Patterns
Insights into Amazonian Biota Origins
- Hernán Vázquez Miranda raises a question regarding fossil records related to Amazonian biota origins; the speaker references studies showing increased angiosperm diversity post-dinosaur extinction.
Future Research Directions
Analysis of Angiosperm Phylogenies
Importance of Detailed Phylogenetic Studies
- The speaker emphasizes the scarcity of detailed phylogenetic studies for angiosperms in South America and the Neotropical region, highlighting a need for more comprehensive research.
- Notable well-studied groups include legumes, Melastomataceae, Orchidaceae, and Annonaceae, indicating a growing body of work that can inform integrative analyses across different plant groups.
Comparative Methodologies Across Regions
- A question arises about applying methodologies to other tropical regions like the Congo Basin or Southeast Asia; the speaker suggests that pan-tropical studies are essential for broader comparisons.
- The speaker anticipates significant advancements in understanding flora across various regions over the next decade, which will facilitate these comparative studies.
Distribution Patterns and Historical Context
- Abel's inquiry about Bignoniaceae distribution in Amazonia and the Andes leads to a discussion on how certain groups from Amazonia have migrated to the Andes and vice versa.
- The speaker notes differing patterns observed in butterflies migrating between these regions, suggesting complex ecological interactions.
Insights on Biogeography and Evolution
- The discussion includes insights into lineages originating from Guyana that may have spread into Amazonia, emphasizing ongoing phylogenetic studies as crucial for understanding these connections.
- Julio Rojas questions the impact of the Isthmus of Panama on biodiversity; this prompts an exploration of historical migration patterns influenced by geological changes.
Historical Migration Patterns Related to Panama
- The speaker explains that Bignoniaceae originated in South America before migrating through Central America back to South America via Antarctica approximately 30 million years ago.
- Multiple migrations from South America to Central America occurred around 20 million years ago when Panama was nearing its connection with South America.
Research Methodology on Ant Aggressiveness
- Delfino Álvaro Campos asks about measuring ant aggressiveness; it is revealed that literature reviews were used rather than direct experiments conducted by collaborators during doctoral research.
Colonization Patterns in Amazonia
Biogeographical Insights on the Amazon and Atlantic Forests
The Evolution of Dry Areas and Species Adaptation
- After 30 million years, dry portions emerged, leading to species adapted to arid conditions appearing in intermediate areas. This marks the development of a proto-Amazon region.
- At this time, South America was not fully forested; the separation between the Amazon and Atlantic forests occurred later with the emergence of dry diagonal regions that prompted morphological adaptations in various species.
Defining Biogeographical Boundaries
- A question arises regarding the biogeographical definition of the Amazon. It is suggested that Brazilian Atlantic forests may be part of it, including regions like Chocó as proposed by Antonelli.
- Currently, the Atlantic forest is not considered part of the Amazon but has historical connections. The Chocó region exhibits distinct plant compositions compared to the Amazon.
Research Gaps and Future Directions
- Ivonne Garzón raises an important point about studying Bignoniaceae trees. The speaker acknowledges a lack of research in this area during their doctoral studies starting in 1996.
- There is hope for future studies focusing on both lianas and trees within Bignoniaceae across neotropical regions as well as Asia and Africa.
Climate Change Impacts on Vulnerable Groups
- Karen Beatriz questions which Bignoniaceae groups might be vulnerable to increasing dryness due to climate change. The anatomy of wood plays a crucial role in survival strategies.
- Certain wood anatomies may predispose some groups to embolism under stress, suggesting that species already inhabiting dry environments could adapt better than those from humid areas.
Subterranean Systems and Their Role
- Discussion includes subterranean systems observed in lianas that may enhance survival in drier conditions through water storage capabilities.
- These systems are noted for having extensive phloem structures that contribute to greater water reserves, indicating an area for further exploration comparing environments across Mexico and Brazil.
Patterns Between Different Flora Regions
- Thiago poses a question about disruption patterns between Atlantic forests and Andes over recent geological timescales. Observations indicate significant overlap among species found across these regions.
- Personal fieldwork experiences highlight how certain species were found both in Madre de Dios (Peru) and Brazil's Atlantic forest, illustrating connectivity between these ecosystems.
Genetic Basis and Ecological Tolerance in Tropical Lianas
Genetic Characteristics of Lianas
- The discussion begins with the genetic basis of specific traits in lianas, particularly focusing on their morphological characteristics such as tendrils.
- Interest is expressed in studying pollen and other morphological features associated with flowers, indicating a broad scope for future research.
Ecological Tolerance in Bignoniaceae
- A question arises regarding the ecological tolerance of various liana species, especially within the Bignoniaceae family, which are prevalent from Brazil to Mexico.
- It is noted that out of approximately 400 species, around 100 exhibit wide ecological tolerance while the remaining 300 have more restricted distributions.
- Familiarity with these common species can aid in identifying most herbarium specimens, highlighting their significance in ecological studies.
Evolutionary History and Soil Types
- A query about the role of soils in Amazonian evolutionary history leads to insights about specialization in white sand regions.
- Specific communities of Bignoniaceae thrive in these sandy areas; however, there is limited information on their evolutionary relationships.
- Some lineages show high diversification after adapting to white sand environments, suggesting a unique evolutionary path worth exploring further.
Nectar Production and Environmental Factors
- The impact of co-evolution on nectar production relative to environmental moisture levels is discussed.
- Findings indicate that humid sites have more nectaries compared to dry ones; nectaries serve protective roles under moist conditions.
- In dry environments, fewer nectaries were expected but results showed no significant differences across populations studied.
Conclusion and Future Research Directions
- Technical difficulties interrupt the session; gratitude is expressed towards participants for their engagement and insightful questions.