Explaining Geographic Range Size by Species Age 53Table 4.1 Continued
Species Mean age SD Median age 95% HPD
(lower)95% HPD
(upper)Piper phytolaccifolium 1.2E–02 2.4E–04 1.2E–02 5.0E–03 2.0E–02
Piper pilibracteum 1.8E–02 2.0E–04 1.7E–02 9.3E–03 2.7E–02
Piper pulchrum 1.6E–02 3.0E–04 1.5E–02 5.6E–03 3.0E–02
Piper reticulatum 4.4E–02 7.4E–04 4.3E–02 2.2E–02 6.9E–02
Piper sabaletasanum 1.4E–02 2.4E–04 1.4E–02 7.6E–03 2.2E–02
Piper schuppii 1.6E–02 3.3E–04 1.6E–02 8.9E–03 2.5E–02
Pipersp1maj674 1.8E–03 3.4E–05 1.5E–03 3.1E–05 4.5E–03
Pipersp2maj689 1.0E–02 2.0E–04 9.7E–03 4.7E–03 1.6E–02
Piper spoliatum 7.4E–03 1.6E–04 7.1E–03 3.3E–03 1.2E–02
Piper subglabribracteatum 1.3E–02 1.9E–04 1.3E–02 5.4E–03 2.2E–02
Piper subpedale 2.4E–02 4.7E–04 2.4E–02 7.9E–03 3.9E–02
Piper terryae 7.1E–03 1.3E–04 6.0E–03 7.1E–04 1.7E–02
Piper tomas–albertoi 8.2E–03 1.2E–04 7.7E–03 2.0E–03 1.5E–02
Piper trianae 7.5E–03 1.4E–04 6.9E–03 1.8E–03 1.4E–02
Piper tricuspe 1.2E–02 2.4E–04 1.2E–02 5.0E–03 2.0E–02
Piper tuberculatum 3.2E–02 6.4E–04 3.1E–02 1.9E–02 4.7E–02
Piper ubatubense 1.7E–02 3.5E–04 1.5E–02 4.3E–03 3.2E–02
Piper umbellatum 2.2E–02 3.1E–04 2.1E–02 1.0E–02 3.4E–02
Piper umbricola 1.2E–02 2.6E–04 1.1E–02 3.1E–03 2.2E–02
Piper unispicatum 7.1E–03 1.3E–04 6.0E–03 7.1E–04 1.7E–02
Piper villosum 2.1E–02 3.6E–04 2.0E–02 1.0E–02 3.4E–02
Piper yanaconasense 1.8E–03 3.4E–05 1.5E–03 3.1E–05 4.5E–03the age-and-area hypothesis. The strength of this
relationshi pis notable in light of the various fac-
tors that can potentially obscure a positive age and
area relationship.
There are some important caveats to this ini-
tial analysis of age and area in a grou pof tro pical
plants. First, our ages were based on divergence
times ofPiperspecies. Our analysis represents only
about 5–10% of the approximately 700 ( Jaramillo
and Manos 2001) to 1150 (Quijano-Abrilet al.
2006) neotropicalPiperspecies. Taxon sampling
affects age estimates, because missing taxa would
alter the estimated divergence times of species if
they were included in the analysis (Linderet al.
2005). Missing taxa can lead to an overestima-
tion of ages (Chown and Gaston 2000, Webb
and Gaston 2000, Joneset al. 2005). However,
given the strength of the positive age and area
relationshi pthat we found based on thePiper
sequences available, and no reason to expect an
inherent bias to the species that were selected to
sequence or to the locations of missing taxa on
the tree, we suspect the positive age and area rela-
tionshi pfound here will be borne out in future
analyses of larger datasets.WHAT DO OTHER TROPICAL
PLANT CLADES TELL US?
Aside fromPiper, there are very few molecular
datasets available for specific clades of tropical
plants that can be effectively used to assess age and
area relationships. Considerable molecular data
have amassed recently on tropical plant lineages
and their divergence dates, but most of these data
examine higher phylogenetic levels (e.g., families
or higher; Renneret al. 2001, Daviset al. 2005,
Lavinet al. 2005) and have focused on the origin
and age of the clades and species that make up
current tropical communities. These data tell an
interesting story, but do not yet provide any clear
expectations for the generality of the kind of age
and area relationshi pfound forPiper.