BBC Wildlife - UK 2020-07)

BEES

56 BBCWildlife July 2020

Toe a r l yn a t u r a l i s t ss o r t i n gt h r o u g ht h e

fossilrecord,thesuddenriseofflowering

plantsduringthelatterpartofthe

Cretaceouswaslongconsideredinexplicable.

Noflowersappearedanywhereinlayer

afterlayerofancientlife,andthenallat

oncetheywereabundantandtheywere

diverse.CharlesDarwinfamouslycalledit

an“abominablemystery,”andconsidered

it a seriouschallengetohisconceptof

evolutionasa slowprocessofincremental

change.Rarelynoted,however,is thatinthe

sameletterwhereDarwinmadehisoften-

quoted‘mystery’comment,hementioned

hiscorrespondencewitha lesser-known

naturalistoftheday,a Frenchmannamed

GastondeSaporta.IndeSaporta’sview,

floweringplantshadindeedevolvedrapidly,

directlyasa resultoftheirinteractions

withflower-visitinginsects,suchasbees.

He theorised that insect pollinators vastly

increasedtherateofintercrossingamong

flowers,leadingquicklytomorespecies.

Darwindidn’tbelieveit.Hepreferred

tothinkthatfloweringplantsmusthave

evolvedslowlysomewhereelse,andthen

dispersedrapidlytotheplaceswherethey

becamefossilised.Darwin’sideainvolved

a hypotheticalcontinentsomewhereinthe

SouthernHemisphere,whereflowerscould

havedevelopedinisolation,thougheven

headmittedthatwas“awretchedlypoor

conjecture”.

Still,theevolutionaryimportanceof

insects remained obscure until a rash of

pollinationstudiesinthelate-19thcentury

showedthatdeSaportahadbeenrightall

along.Mostofthatresearchinvolvedbees

• howtheynotonlypromotedout-crossing,
  asdeSaportahadsuspected,buthowplants
  competedanddiversifiedinanefforttowoo
  theirbuzzingvisitors.
  Flowertraitsasfundamentalascolour,
  shapeandfragranceoftenboildowntothe
  proclivitiesofbees,andcateringtothat
  evolutionarypressurehelpedflowering
  plantsexpandtodominateover 90 percent
  oftheEarth’sterrestrialflora.Theresults
  canbeseeneverywherefrommountain
  meadowstorainforestcanopiestothe
  windowdisplayat thenearestflowershop.
  Butwhatis lesswellknownis howtherapid
  diversificationoffloweringplantsled,in
  turn,toanincrediblediversityofbees.
  Recenttaxonomicestimatesputthe
  numberofdifferentbeesintheworldat
  morethan20,000species,morethanall
  themammalsandbirdscombined.This
  figure surprises many people, because

Whilewetendtothinkofpollinationasa

winforbeesandplantsalike,thereisno

smallamountoftrickeryatwork.Many

orchidsdeceivetheirbeevisitors,luring

theminwithfragrant,colourfulflowers

thatcontainnonectarorusablepollen

whatsoever. The most famous example

maybethebeeorchids,theblossoms

ofwhichtakeontheshape,texture,and

odourofparticularfemalebees.Malesthen

unwittinglytransferpollenastheymove

fromplanttoplant,mountingtheflowers

ina pollinationscenariodefinedbya telling

botanical term – pseudocopulation.

Orchids & bees

Thisground-nestingbee

isintensivelymanaged

asa pollinatorforalfalfa,

withonenestingbedin

Washingtongrowingto5.3

million nesting females.

ALKALIBEE

NOMIA MELANDERI

Above,left:a

honeybeeemerges

froma broodcell.

Above:a male

bumblebeeattempts

tomatewitha bee

orchid,mistaking

it for a female.

Recentestimatesputthe

numberofdifferentbees

intheworldatmore than

20,000 species.

Left to right: Ingo Arndt/NPL; Premaphotos/Alamy; Emanuele Biggi/FLPA; Solvin Zankl/NPL; Kim Taylor/NPL