Grimaldi  and  Engel  2005

Current  Views  on  Insect  Diversity

Mina Krenz Dan Chou

Phylogenomics  resolves  the  timing  and  pa@ern  of  insect  

evolutionMisof 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

NeopteraPolyneoptera, 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:  Diversifica6on  in  the  Age  of  Angiosperms  

Moreau  C.S.,  Bell  C.D.,  Vila  R.,  Archibald  B.,  Pierce  N.E.    

Ants  

•  Key  roles  in  symbio6c  interac6ons  •  Soil  Aera6on  •  Nutrient  cycling  •  Dominant  in  terrestrial  landscape:  – 11,800  species  –  evolu6onary  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  6me  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  

Sta6s6cal  Analysis    

•  Maximum  likelihood  bootstrap  •  Bayesian  posterior  probabili6es  •  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  Monophyle6c  with  strong  support  – Leptanillinae  (100%)  

•  Early  morphological  phylogenies  do  not  show  this  at  basal  posi6on  •  Basal  posi6on  shows  early  tergosternal  fusion  of  3rd  &  4th  abdominal  segments,  lost  secondarily    •  These  characters  are  labile/homoplasious  

•  19  recovered  as  monophyle6c  •  Cerapachyinae  paraphyly  

Bolton  =    Proposed  “poneromorph”  clade  

-‐Amblyoponinae  -‐Ectatomminae  -‐Heteroponerinae  -‐Paraponerinae  -‐Ponerinae  -‐Procer6inae  

 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  -‐Procer6inae  

 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  es6mate  based  on  fossil  record  

Previous  studies  showing  early  history  of  Formicidae  

•  Previous  studies  by  Brady  and  Ward  used  molecular  data  to  arrive  at  an  es6mate  of  130-‐140  Million  years  old  – But….  Although  these  are  similar  dates  the  Moreau  et  al.  study  used:  • Wider  sampling    •  Addi6onal  fossils  

à  Leads  to  an  even  older  es6mate!  (140-‐168  mil  years  old)    

Results  •  Diversifica6on  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  evolu6on  

 

Correspondence  with  Angiosperm  radia6on  

•  Rise  in  Angiosperm  dominated  forests  was  essen6al  to  the  diversifica6on  of  ants    – Why  would  this  happen?    

Discussion  

Given  the  importance  of  plants  in  determining  the  6ming  of  evolved  traits  in  insects,  as  well  as  human’s  adverse  impact  on  nature  (eg:  deforesta6on),  is  it  possible  that  insect  evolu6on  is  being  dampened?  Would  insects  be  bemer  off  without  humans  or  are  all  organisms  interconnected  and  important  for  others  to  thrive,  despite  some  downfalls?      

Lineages  through  6me  plot  

•  LTT  plot:  Accumula6on  of  ant  lineages  around  ~100  (following  angiosperm  radia6on)  – Also  seen  in  Coleopteran  &  Hemipteran  diversifica6on  

Is  there  something  wrong  with  the  way  this    Histogram  was  constructed?  

Are  LTT  graphs  a  good  method  for  researchers  to  infer  phylogene6c  rela6onships?  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  – Shio  in  diet  à  evolu6on  of  social  behaviors  

 

Significance?  

•  Evolu6onary  inves6ga6on  of  life  history,  ecology,  biogeography  in  order  to:  – Observe  pamerns  of  diversifica6on  and  distribu6on  of  this  dominant  group  of  insects  

•  This  highlights  need  for  conserva6on  of  ant  habitats  to  foster  biodiversity  to  further  research  poorly  understood  evolu6onary  history  

The  Fossil  record  and  Macroevolu6onary  history  of  

beetles  Smith  D.M.  and  Marcot  J.D.    

Main  points  •  Compiled  a  database  of  

global  beetle  fossil  data  in  order  to  study  evolu6onary  history  

•  Polyphaga  responsible  for  most  taxononmic  richness  of  beetles    –  Also  increase  in  diversifica6on  rate  in  Cretaceous  like  Formicidae,  but  not  due  to  Angiosperm  radia6on  

•  Observed  mechanisms  that  inhibited  beetle  ex6nc6on  rather  than  mechanisms  promo6ng  specia6on    

Polyphagan  vs.  Non-‐Polyphagan  diversifica6on  

•  Degree  of  dietary  varia6on  and  specializa6on  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  origina6on  rates  and  higher  ex6nc6on  rates  than  Polyphaga  

•  Polyphagans  surpass  richness  of  non-‐polyphagans  in  Jurassic    –  Established  early  and  longlived  (family  ex6nc6on  rate  of  zero)  

Non-‐polyphagans  reach  family  richness  peak  

Polyphagans  diversifica6on  rate  surpasses  that  of  non-‐polyphagans  (who  have  a  higher  ex6nc6on  rate  in  this  6me  period)  

Increase  in  diversifica6on  rate  of  Polyphagans  

Should  this  middle-‐cretacean  increase  in  the  diversifica6on  rate  of  Polyphagans  be  amributed  to  the  rise  in  Angiosperms  during  the  same  6me  period?  Like  that  of  the  Ant  paper?  

Origin  of  non-‐polyphagans  

Amber  deposits    

•  Instead  of  amribu6ng  this  to  Angiosperm  radia6on,  Smith  and  Marcot  connect  this  pulse  of  Polyphagan  origina6on  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  suscep6ble  to  ex6nc6on  

•  Ability  to  change  geographical  distribu6on  in  response  to  climate  change  – Diet  

 

Discussion  

Why  must  phylogenies  always  be  regarded  as  working  hypotheses  and  considered  with  a  certain  level  of  scru6ny?    

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.