zoology draft

Primary Literature Summary

 Each student will write a short (250–300 word, excluding the classification and citation) summary of a

paper from the primary scientific literature which focuses upon a particular invertebrate species. Below

is a sample summary that will help you know how to approach this assignment.

Example Literature Summary*

CLASSIFICATION

 1) Ph. Arthropoda, SubPh. Crustacea, Cl. Malacostraca, SubCl. Eumalacostraca, SupOr. Peracarida, Or.

Amphipoda, SubOr. Corophioidea, Fam. Ischyroceridae, Gen. Microjassa

SUMMARY OF PAPER

 2) Conlan, K.E. 1995. Thumb evolution in the amphipod genus Microjassa Stebbing

(Corophioidea:Ischyroceridae). Journal of Crustacean Biology 15:693-702.

 3) Claws have evolved many times in the Crustacea, but how did they evolve from the jointed segments

of a simple walking leg? The amphipod genus Microjassa helps us study claw evolution because claw

form varies from thumbless in some species (simple clasping or subchelate) to fully thumbed in other

species (truly claw-like or chelate).

 4) Males use sexually dimorphic second gnathopods (claws) to grasp females prior to the molt when

mating occurs. This phenomenon, called mate guarding, occurs in many crustacean species. In some

species of Microjassa, the terminal leg segment (dactyl) simply folds tightly against the adjacent leg

segment (propus) to form a hook-like clasping structure. In others, a rigid projection extends from the

terminal end of the propus, forming a ‘thumb’ against which the dactyl may close. This clasping

structure looks surprisingly like the fully-developed claws of crabs and lobsters.

 5) Conlan conducted a phylogenetic analysis of nine species, using 20 morphological characters. When

gnathopod form was mapped onto her cladogram, she discovered a gradual evolutionary trend from

unthumbed to fully-thumbed ‘claws’. The most derived species even had multiple thumbs!

 6) Conlan concludes that the claw-like second gnathopods in male Microjassa evolved from simple

clasping limbs by the gradual amplification of a rigid, thumb-like projection of the propus. This study

illustrates nicely the value of cladistics analysis for inferring the history of morphological evolution and

how a key morphological adaptation (claws) evolved via gradual transformation of a walking leg.

 7) (240 words)

* Permission to use this example and exercise was granted by Richard Palmer, Systematics and Evolution Group,

Department of Biological Sciences, University of Alberta

EXPLANATION OF THE NUMBERED PARTS IN THE SUMMARY ABOVE

(for ease of reviewing, please number these parts in your own report)

 1) Classification: This classification must include all of the appropriate taxonomic ranks above the level

of genus and species.

 2) Full citation [all authors, year, full title of paper (no abbreviations), full journal title, volume, pages];

citation style should follow that of the example on the previous page.

 3) Why did the authors do the study? These 2 – 4 sentences should include a clear and simple question

(e.g., stated in the form of a question or as two or more alternative hypotheses) that identifies the general

puzzle the paper attempts to solve (i.e., the broader relevance; note that sometimes the authors

themselves may not even do this very well!). The goal here is to construct the opening sentences so the

reader wants to read the rest of the annotation.

 4) These 2-4 sentences should give background information required to understand the study’s

significance.

 5) 3-5 sentences should summarize the main methods and results; include quantitative results where

possible.

 6) These 2-3 sentences should summarize the general conclusions of the study, including the answer to

the question stated at the beginning.

 7) Use your word-processor to count the words and include the word count after each annotation.

Exclude the title and citation in your word count.