Range size, taxon age and hotspots of neoendemism in the California flora

Abstract

Aim Sustaining biological diversity requires the protection of the ecological, evolutionary and landscape‐level processes that generate it. Here, we identify areas of high neoendemism in a global diversity hotspot, the California flora, using range size data and molecular‐based estimates of taxon age. Location California, USA. Methods We compiled distribution and range size data for all plant taxa endemic to California and internal transcribed spacer (ITS)‐based age estimates for 337 putative neoendemics (15% of the endemic flora). This information was combined to identify areas in the state with high proportions of young and restricted‐range taxa. We overlaid the distribution of neoendemic hotspots on maps of currently protected lands and also explored correlations between our diversity measures and climate. Results The central coast of California, the Sierra Nevada and the San Bernardino Range contained endemics with the most restricted distributions on average, while areas in the Desert and Great Basin provinces found within the state were composed of the youngest neoendemics on average. Diversity measures that took age and range size into account shifted the estimate of highest endemic diversity in the state towards the Desert and Great Basin regions relative to simple counts of endemic species richness. Our diversity measures were poorly correlated with climate and topographic heterogeneity. Main conclusions Substantial portions of California with high levels of plant neoendemism fall outside of protected lands, indicating that additional action will be needed to preserve the geographic areas apparently associated with high rates of plant diversification. The neoendemic flora of the deserts appears particularly young in our analyses, which may reflect the relatively recent origin of desert environments within the state.

Molecular data support placement of Cameronia in Ostropomycetidae (Lecanoromycetes, Ascomycota)

“…Examples include the genera Jarmania Kantvilas (Kantvilas 1996), Meridianelia Kantvilas & Lumbsch (Kantvilas and Lumbsch 2009), Siphulella Kantvilas, Elix & P. James (Kantvilas et al 1992), Tasmidella Kantvilas, Hafellner & Elix , and several species of Cladia Elix 1987,1999) and thelotremoid Graphidaceae (Kantvilas and Vezda 2000;Mangold et al 2009). In general, endemism can be either the result of survival of relict taxa (palaeoendemism) or recent speciation events (neoendemism) (Brandley et al 2010;Brooks et al 2006;Goldberg et al 2005;Jans-sen et al 2008;Kier et al 2009;Kraft et al 2010;Lamoreux et al 2006;Olson et al 2001;Qian 2001). The reasons for the relatively large amount of endemic taxa in Tasmania are not well understood.…”

Phylogenetic measures of biodiversity and neo- and paleo-endemism in Australian Acacia

“…It has long been recognized that there are two kinds of endemic species: neo-endemics-recently diverged species that are endemic because of lack of dispersal/migration out of their ancestral area; and paleo-endemics-old species that were perhaps more widespread in the past and are now restricted to a local region [18][19][20] . This traditional taxonomic formulation is suboptimal for two reasons.…”

Local patterns of diversity in California northern coastal scrub

“…These results emphasize the importance of plant conservation in California's coastal zone, especially in unprotected areas, which tend to host high concentrations of rare and endemic taxa (Kraft et al., 2010; Pavlik & Skinner, 1994). Coastal bluffs and terraces along the coast of California have high conservation value, as these areas have been heavily impacted by development and agriculture.…”

“…Combined, these studies suggest where intensive conservation efforts should focus. Endemic species richness is concentrated in coastal areas, particularly in the San Francisco Bay Area (Ackerly, 2009; Kraft et al., 2010), and is especially concentrated along the immediate coast. Within northern coastal scrub, plant diversity and species richness were consistently higher in coastal plots than in inland plots.…”

“…Regional patterns of plant diversity in MTCs may be explained both by phylogenetic analysis, in relation to historic environmental change, and by ecological analysis, in relation to environmental factors influencing contemporary species coexistence (Linder, 1991). Explosive Quaternary species radiations occurred in all MTCs, in response to drought, fire, and other stressors associated with aridification, while low extinction rates or radiations of older lineages were associated with refugia from these climatic extremes or refugia from cooling and glaciation during ice ages (Ackerly, 2009; Cowling & Lombard, 2002; Keeley & Swift, 1995; Kraft, Baldwin, & Ackerly, 2010; Raven & Axelrod, 1978; Rundel et al., 2016; Stebbins & Major, 1965). Contemporary patterns of plant diversity in MTCs have been shown to be positively correlated with environmental heterogeneity in soils, topography, precipitation, and temperature (Casazza, Zappa, Mariotti, Médail, & Minuto, 2008; Harrison, Viers, & Quinn, 2008; Linder, 1991; Richerson & Lum, 1980).…”