Highlights from our inaugural issue

It’s here! The first issue of our excit­ing new evol­u­tion­ary bio­logy journ­al is now online, fea­tur­ing sex, sperm, spe­ci­ation, and more! All papers are avail­able to read right now, fully open access, via the Evol­u­tion Let­ters website

Here is what our inaug­ur­al issue has in store…

Gib­son, Delph, & Lively: The two-fold cost of sex: exper­i­ment­al evid­ence from a nat­ur­al system

Photo © Bart Zijl­stra – www.bartzijlstra.com

Over­view

• The two-fold cost of sex was first pro­posed by Maynard Smith, who poin­ted out that sexu­al females must spend 50% of their resources on mak­ing sons, but those sons will pro­duce no off­spring them­selves. As a res­ult, asexu­al lin­eages should out­com­pete sexu­al lin­eages. Maynard Smith’s the­ory raised one of the most inter­est­ing ques­tions in evol­u­tion­ary bio­logy: why is there sex?
• To date, the cost of sex has not been dir­ectly estim­ated, so this pop­u­lar idea has remained untested for over 40 years.
• In this new study, Gib­son et al. provide the first estim­ate of the cost of sex by meas­ur­ing fre­quen­cies of sexu­al and asexu­al snails in nat­ur­al, mixed populations.
• They show that the increased fre­quency of asexu­als closely matches that pre­dicted by a two-fold cost, val­id­at­ing found­a­tion­al the­ory in evol­u­tion­ary biology.

Read the study in full here.

Gas­par­ini, Dos­selli, & Evans: Sperm stor­age by males causes changes in sperm phen­o­type that influ­ence the repro­duct­ive fit­ness of males and their adult sons.

Photo © Clelia Gasparini

Over­view

• Delays between gam­ete pro­duc­tion and fer­til­isa­tion are inev­it­able in intern­ally fer­til­ising spe­cies, and males often have to store sperm in their repro­duct­ive tract while they seek out copulations.
• Gas­par­ini et al. show that in gup­pies, old sperm (i.e. those stored by the male for longer dur­a­tions before ejac­u­la­tion) are not only at a dis­ad­vant­age in sperm com­pet­i­tion, but also pro­duce sons with slow-swim­ming sperm.
• Males that stored sperm for longer before insem­in­at­ing females had a great­er num­ber of slow swim­ming sperm and lower patern­ity suc­cess in com­pet­it­ive insem­in­a­tion trials.
• Fas­cin­at­ingly, sons pro­duced by these males also had slow swim­ming sperm, demon­strat­ing that sperm (or sem­in­al flu­id) age­ing may have con­sid­er­able trans­gen­er­a­tion­al effects.

Read the study in full here.

Wad­gy­mar, Daws, & Ander­son: Integ­rat­ing viab­il­ity and fecund­ity selec­tion to illu­min­ate the adapt­ive nature of genet­ic clines.

Photo © Ben Ammon

Over­view

• Although there have been many estim­ates of selec­tion in nat­ur­al pop­u­la­tions, stud­ies have rarely examined both spa­tial and tem­por­al dynam­ics at the same time, espe­cially across dif­fer­ent life his­tory stages.
• Here, Wad­gy­mar et al. assess spa­tial and tem­por­al pat­terns of nat­ur­al selec­tion in the sub­alpine per­en­ni­al forb Boech­era stricta, using exper­i­ment­al gar­dens across a steep envir­on­ment­al gradi­ent, to test the hypo­thes­is that nat­ur­al selec­tion fluc­tu­ates around loc­al phen­o­typ­ic optima.
• Boech­era stricta was found to exhib­it sig­ni­fic­ant genet­ic­ally-based clines in physiolo­gic­al, mor­pho­lo­gic­al, and phen­o­lo­gic­al traits, with inter­me­di­ate trait val­ues being favoured – provid­ing evid­ence for sta­bil­ising selection.
• Genet­ic­ally-based clines are likely to have evolved in response to long-term spa­tial vari­ation in selec­tion across steep elev­a­tion­al gradients.

Read the study in full here.

Green­berg & Moo­ers: Link­ing spe­ci­ation to extinc­tion: Diver­si­fic­a­tion raises con­tem­por­ary extinc­tion risk in amphibians.

Photo © Dan Greenberg

Over­view

• Amphi­bi­ans exhib­it one of the highest rates of mod­ern extinc­tion of all vertebrates.
• By examin­ing evol­u­tion­ary pat­terns of mod­ern extinc­tion risk across more than 300 amphi­bi­an gen­era, Green­berg & Moo­ers show that lin­eages with high ongo­ing diver­si­fic­a­tion are at great­er risk of extinc­tion than slowly diver­si­fy­ing lineages.
• This sup­ports the idea that lin­eages that spe­ci­ate read­ily may also lose spe­cies read­ily, due to char­ac­ter­ist­ics that pro­mote both spe­ci­ation and extinc­tion (e.g. spe­cial­isa­tion and isolation).
• From a con­ser­va­tion per­spect­ive, this clustered extinc­tion threat means that pro­tect­ing a rel­at­ively small num­ber of spe­cies may go a long way towards pre­serving amphi­bi­an phylo­gen­et­ic diversity.

Read the study in full here.

O’Brien & Wolf: The coad­apt­a­tion the­ory for gen­om­ic imprinting.

Photo © W.H. Calvin

Over­view

• Gen­om­ic imprint­ing is a pecu­li­ar phe­nomen­on occur­ring in a sub­set of genes, where the expres­sion of each gene copy depends on wheth­er is came from the moth­er or father.
• Here, O’Brien & Wolf address the ques­tion of why gen­om­ic imprint­ing evolved, using a simple math­em­at­ic­al mod­el where an animal’s suc­cess in social inter­ac­tions depends on the com­bin­a­tion of its own traits, and those expressed by the anim­als it inter­acts with.
• The study shows that when the related­ness of inter­act­ing anim­als dif­fers through their mater­nally and paternally inher­ited genes, selec­tion favours expres­sion of the gene through which related­ness is high­er. This enhances the com­pat­ib­il­ity of the genes expressed by both individuals.
• O’Bri­en & Wolf’s gen­er­al coad­apt­a­tion the­ory demon­strates that gen­om­ic imprint­ing can evolve because it coordin­ates the traits of inter­act­ing anim­als. lead­ing to more suc­cess­ful social interactions.

Read the study in full here.

Finally, don’t miss Edit­or-in-chief Jon Slate’s intro­duc­tion to the journ­al, telling the story of how Evol­u­tion Let­ters came to be, and out­lining our vis­ion for the future. We hope you enjoy our first issue.