Grimaldi and Engel 2005 Current Views on Insect Diversity
Mina Krenz Dan Chou Phylogenomics resolves the timing and pa ern of insect evolution
Misof B. et al 2014
Why Study Insect Phylogeny? • Insects represent one of the earliest animals to make their way to terrestrial and aquatic environments • Due to having a multitude of species, the phylogeny of insects are still well debated to this day • Must reconstruct timelines of insect diversification in order to understand the changes in their physiology and morphology Summary of the methods • 1478 nuclear genes from 144 extant taxa • More than 2.5 gigabases from each of the 103 species they studied • Estimating divergence events via 37 fossil records • Maximum Likelihood of mutations in DNA and amino acids (rather than maximum parsimony) Boot-Strapping • Acts as a resampling method in statistics • Selects a number of base pairs to see how sensitive results are to exclusion of some data. • Resampling data to see how robust and strong it is against randomization. • See conflict in data by providing: confidence intervals, variance, errors, etc. Paleoptera Relationship between Odonates and Ephemeroptera • The data indicates that Odonata and Ephemeroptera are nested within the Paleoptera • However, this analysis is supported by a low boot- strapping • What might this mean? o Odonates and Ephemeroptera possibly paraphyletic? • Why is it difficult to determine the relationships in Paleoptera? Relationship between Odonates and Ephemeroptera
• Paleoptera only have two extant lineages, even though they derive from all the way back in the Carboniferous • Most likely Odonata and Ephemeroptera divided shortly after Paleoptera and Neoptera diverged, so huge variance between two Orders • Long time span for Ephemeroptera and Odonata to diverge through gene mutations Neoptera
Polyneoptera, Holometabola/Endometabolous and Paraneoptera*** Holometabolous • Strong statistical support for the well-nested group of Holometabolous • High diversity of Hymenoptera, Diptera, and Lepidoptera in early Cretaceous Polyneoptera • Previous study supported the monophyly in groups such as Hexapoda, Insecta, Pterygota, Neoptera, Paraneoptera, and Holometabolous • However, there was weaker support for a monophyletic Polyneoptera (Kjer et al 2006)
Polyneoptera • Misof et al strongly support the monophyletic group of the Polyneoptera • Boom in diversity of Blattodea, Mantodea, and Plasmodea in Permean extinction. Polyneoptera
Holometabolous /Endopterygota Paraneoptera • The results suggest a diverge of Psocodea from the rest of the Paraneoptera, forming a paraphyletic group • The results show that Psocodea in fact a sister taxa to the Holometabolous • Yet this claim does not have statistical support • Why include this data if it is not backed? Age of Psocodea Taxa? • The study claims that that parasitic lice (Menopan and Pediculus) arose in around 53mya with the emergence of the avian and mammalian taxa. • However, their analysis looks at the crown clade, rather than the stem clade from the remaining • Stem shows an arrival of parasitic lice ~130 mya, at the arrival of feathered theropod dinosaurs
Food for Thought • In your opinion, how to these results compare to what has been presented in class/in the book (i.e. what critiques do you have for this study)? • What other data or tests could have been used to make this study more reliable? • Study of genomics is still a fairly new field of science • Science based on certain assumptions and interpretations of the data; continuously changing and growing Gullan and Cranston, 2014 Food for Thought • What evolutionary/environmental factors may have given rise to these diverse groups? Phylogeny of the Ants: Diversifica on in the Age of Angiosperms Moreau C.S., Bell C.D., Vila R., Archibald B., Pierce N.E. Ants
• Key roles in symbio c interac ons • Soil Aera on • Nutrient cycling • Dominant in terrestrial landscape: – 11,800 species – evolu onary history poorly resolved Main points
• Extant ants arose much earlier than previously proposed: 75-125 mya • Began to diversify late Cretaceous – Early Eocene – 60-100 mya • This me period corresponds with the rise of angiosperms and many herbivorous insects Past phylogenies of Family Formicidae
• Past phylogenies proposed using morphological traits and molecular data with less data • This phylogeny constructed from large-scale molecular data – 4.5 kb of sequence data – Six gene regions from 139 of 288 extant genera • Represents 19 of 20 subfamilies Sta s cal Analysis
• Maximum likelihood bootstrap • Bayesian posterior probabili es • Maximum parsimony bootstrap Major lineages in Formicidae
• Three main clades: – Leptanilloid (sister taxon to all other ants) • One subfamily: Leptanillinae – Poneroid • 5 subfamilies • Amblyoponinae lacked support – Formicoid • Contains remaining 13 subfamilies
Monophyly • 14 recovered as Monophyle c with strong support – Leptanillinae (100%) • Early morphological phylogenies do not show this at basal posi on • Basal posi on shows early tergosternal fusion of 3rd & 4th abdominal segments, lost secondarily • These characters are labile/homoplasious • 19 recovered as monophyle c • Cerapachyinae paraphyly
Bolton = Proposed “poneromorph” clade -Amblyoponinae -Ectatomminae -Heteroponerinae -Paraponerinae -Ponerinae -Procer inae
These results exclude Ectatomminae and Heteroponerinae, but add Agroecomyrmecinae -Represented by Tatuidris Tatusia
Bolton = Proposed “poneromorph” clade using morphological analyses -Amblyoponinae -Ectatomminae -Heteroponerinae -Paraponerinae -Ponerinae -Procer inae
These results exclude Ectatomminae and Heteroponerinae, but add Agroecomyrmecinae
Historical placement of Heteroponerinae and Ectatomminae • Heteroponerinae in formicoid clade is unexpected – Historically in poneromorph clade – Same goes for Ectatomminae (closely related to Heteroponerinae) Fossil record
• Oldest reliable fossils containing Formicidae are ~100 million yrs. old from early cretaceous in French & Burnese ambers • Implies earlier history than expected of Formicidae • Results show an even earlier history…
140-168 Million years old! Much older than previous es mate based on fossil record Previous studies showing early history of Formicidae • Previous studies by Brady and Ward used molecular data to arrive at an es mate of 130-140 Million years old – But…. Although these are similar dates the Moreau et al. study used: • Wider sampling • Addi onal fossils à Leads to an even older es mate! (140-168 mil years old) Results • Diversifica on of major Formicidae lineages ocurred: – beginning of Early Paleoceneto Late cretaceous (60-100 Mya) • Ancestors of major subfamilies present 75-125 mya • If they were present much earlier, why did they take so long to diversify? • Previous fossil record indicates later evolu on
Correspondence with Angiosperm radia on • Rise in Angiosperm dominated forests was essen al to the diversifica on of ants – Why would this happen?
Discussion
Given the importance of plants in determining the ming of evolved traits in insects, as well as human’s adverse impact on nature (eg: deforesta on), is it possible that insect evolu on is being dampened? Would insects be be er off without humans or are all organisms interconnected and important for others to thrive, despite some downfalls?
Lineages through me plot
• LTT plot: Accumula on of ant lineages around ~100 (following angiosperm radia on) – Also seen in Coleopteran & Hemipteran diversifica on Is there something wrong with the way this Histogram was constructed? Are LTT graphs a good method for researchers to infer phylogene c rela onships? Why or why not? Why the correla on between Angiosperm radia on and diversifica on of Formicidae?
• Forests are more diverse – Wider array of habitats • Expansion of herbivorous insects – Provided direct food source – Indirect food source: honeydew – Shi in diet à evolu on of social behaviors
Significance?
• Evolu onary inves ga on of life history, ecology, biogeography in order to: – Observe pa erns of diversifica on and distribu on of this dominant group of insects • This highlights need for conserva on of ant habitats to foster biodiversity to further research poorly understood evolu onary history The Fossil record and Macroevolu onary history of beetles Smith D.M. and Marcot J.D. Main points • Compiled a database of global beetle fossil data in order to study evolu onary history • Polyphaga responsible for most taxononmic richness of beetles – Also increase in diversifica on rate in Cretaceous like Formicidae, but not due to Angiosperm radia on • Observed mechanisms that inhibited beetle ex nc on rather than mechanisms promo ng specia on Polyphagan vs. Non-Polyphagan diversifica on • Degree of dietary varia on and specializa on within subgroups in Polyphaga – Algae, fluid feeders, carnivores, xylophages • Non-polyphagans first to appear in fossil record – Reach peak of family richness in Triassic – Jurassic: low origina on rates and higher ex nc on rates than Polyphaga • Polyphagans surpass richness of non- polyphagans in Jurassic – Established early and longlived (family ex nc on rate of zero) Increase in diversifica on rate of Polyphagans Polyphagans diversifica on rate surpasses that of non-polyphagans (who have a higher ex nc on rate in this me period) Non-polyphagans reach family richness peak
Origin of non-polyphagans
Should this middle-cretacean increase in the diversifica on rate of Polyphagans be a ributed to the rise in Angiosperms during the same me period? Like that of the Ant paper?
Amber deposits
• Instead of a ribu ng this to Angiosperm radia on, Smith and Marcot connect this pulse of Polyphagan origina on to: – First ocurrence of beetle-bearing amber deposits in fossil record – They used different types of fossils in their database: lacustrine deposits
Why Polyphaga beetles may not be as suscep ble to ex nc on
• Ability to change geographical distribu on in response to climate change – Diet
Discussion
Why must phylogenies always be regarded as working hypotheses and considered with a certain level of scru ny?
References • Main Papers: o Misof et al. 2014. Phylogenomics resolves the timing and pattern of insect evolution. Science 346.620: 763-767 o Moreau C.S., Bell C.D., Vila R., Archibald S.B, Pierce N.E.. 2006. Phylogeny of the Ants: Diversification in the Age of Angiosperms. Science 312: 101-104. • Resources: o Grimaldi D. and Engel M.S. 2005. Evolution of the Insects. Cambridge University Press: New York. o Kjer K.M. Carle F.L. Litman J., and Ware J. 2006. A Molecular Phylogeny of Hexapoda. Arthropod Systematics & Phylogeny 61(1): 35-44. o Smith D.M and Marcot J.D. 2015. The fossil record and macroevolutionary history of the beetles. Proc. R. Soc. B 282: 1-8.