Everyone loves a refreshing glass of gin and tonic. I personally like it with a wedge of lime and frozen tonic water. As a gin and tonic lover , it concerns me whether I would be able to enjoy the same drink in the next few decades.
Gin is made from juniper berries ( Juniperus communis) and it is one of the most popular spirits around the world. A recent published paper in PNAS gave us a little insight into the evolutionary history of these “magical” berries ( it was once used as a medical remedy, see here ) and perhaps help us make a guess of the fate of these (very!) important crop .
Juniper berries are belongs to a family called Cupressaceae and it has an incredible range of physical and environmental preference. Some of the Cupressaceae prefer a hydrated environment such as water-logged soil and the others live in dry climates such as northern and southern hemispheres .
Juniper trees are like all other woody plants; they are constrained by the temperature and water availability. Woody plants have transporting tubes called xylem ; and it’s primary role is to transport water around the plant. The scientists examined the water activity in the xylem and compared its composition with other members of the Cupressaceae family. They found Juniperus trees are extremely drought tolerant and possiblity one of reason why it has become the most diversified member of the family. Its special ability to adapt to dry conditions allow it to expand through Europe,North America and North Africa through it evolutionary history ; while the other members of the family are much restricted by its climate adaptation and remain in humid areas.
You might think Juniperus trees have got it all and is the king specie of the Cupressaceae family. Not quite, its drought tolerant capability came with an expense. Juniperus trees are less efficient in transporting and pumping water and as a result, it has a reduced photosynthetic yield. The price of being drought-resistant means it has to increase the carbon investment in the xylem tissue and therefore, reduce the efficiency of xylem transportation. Also, it diminished the surface area of the leaves to reduce moisture lost through its pores ( stomata) . As a result, the leaves we see today have become short green spikes (see picture) . Another group of scientists believes the leaves have shrunk in sixfold from its original size. Both of these physical features have reduce its ability to photosynthesis, but it allows it to thrive in a new habitat. Over the evolutionary time, the trees have adjusted its leaf size to what we believe to be optimal, but the cost of survival is slow growth and short.
So, what does it all mean? This is the global climate change projection for 2050 by Intergovernmental Panel on Climate Change (IPCC) under the worst scenario :
Intensity of precipitation events is projected to increase, particularly in tropical and high latitude areas that experience increases in mean precipitation. Even in areas where mean precipitation decreases (most subtropical and mid-latitude regions), precipitation intensity is projected to increase but there would be longer periods between rainfall events. There is a tendency for drying of the mid-continental areas during summer, indicating a greater risk of droughts in those regions. Precipitation extremes increase more than does the mean in most tropical and mid- and high-latitude areas.
Looks like Juniperus trees are going to survive the extreme weather condition (if this projection is accurate – an ongoing debate in the scientific community ). Not so lucky for other moisture sensitive plants like tomatoes , but at least we know gin and tonic is going to be around for the next few decades.